### 12th Standard CBSE Chemistry Study material & Free Online Practice Tests - View Model Question Papers with Solutions for Class 12 Session 2019 - 2020 CBSE [ Chapter , Marks , Book Back, Creative & Term Based Questions Papers - Syllabus, Study Materials, MCQ's Practice Tests etc..]

#### 12th Standard CBSE Chemistry Public Exam Model Question 2020 - by Archana Singh - Deoghar - View & Read

• 1)

In an ionic compound A+X-,the radii of A+ and X- ions are 1.0pm and 2.0pm respectively.The volume of the unit cell of the crystal AX will be

• 2)

For a weak monobasic acid, if pKa = 4, then at a concentration of 0.01 M of the acib solution, the van't Hoff factor is

• 3)

Rust is a mixture of

• 4)

At high pressure, the following reaction is of zero order.
2NH3  $\xrightarrow [ Platinum\quad catalyst ]{ 1130K }$ (g) N2(g) + 3H2(g)
Which of the following options are correct for this reaction ?

• 5)

The correct order of adsorption of the gases studied will be

#### 12th Standard CBSE Chemistry Public Exam Sample Question 2020 - by Archana Singh - Deoghar - View & Read

• 1)

In which of the  following arrangements octahedral voids are formed?

• 2)

The vapour pressure of a dilute solution of a solute is not influenced by

• 3)

Conductivity k, is equal to ---------

• 4)

Collision Theory is applicable to

• 5)

#### 12th Standard CBSE Chemistry Public Exam Important Question 2019-2020 - by Archana Singh - Deoghar - View & Read

• 1)

A metal has cubic close packed (ccp) arrangement,the layer sequence of which is shown below: A face diagonal passes through the centre of atom 4 and the centre(s) of which other atom(s)?

• 2)

Increasing the temperature of an aqueous solution will cause

• 3)

Given below are the half cell reactions :

${ Mn }^{ 2+ }+{ 2e }^{ - }\longrightarrow Mn,\quad { \quad \quad \quad \quad E }^{ 0 }=-1.18V\\ 2({ Mn }^{ 3+ }+{ e }^{ - }\longrightarrow { Mn }^{ 2+ }),\quad \quad { E }^{ 0 }\quad =+1.51V\quad$

The E0 for $3{ Mn }^{ 2+ }\longrightarrow Mn+2{ Mn }^{ 3+ }$ will be

• 4)

When ethyl acetate was hydrolysed in presence of 0.1 N HCI, the rate constant was found to be 5.40 $\times$ 10-5 s-1 . From these values we can say that

• 5)

What happens when a lyophilic sol is added to a lyophobic sol?

#### 12th Standard Chemistry Board Exam Sample Question 2020 - by Archana Singh - Deoghar - View & Read

• 1)

In a solid 'AB' having NaCl structure, 'A' atoms occupy the corners of the cubic unit cell.If all the face-centred atoms along one of the axes are removed,then the resultant stoichiometry of the solid is

• 2)

The sequence of ionic mobility in the aqueous solution is

• 3)

At high pressure, the following reaction is of zero order.
2NH3  $\xrightarrow [ Platinum\quad catalyst ]{ 1130K }$ (g) N2(g) + 3H2(g)
Which of the following options are correct for this reaction ?

• 4)

An emulsion cannot be broken by.........................and......................... .

#### 12th Standard Chemistry Board Exam Model Question 2019-2020 - by Archana Singh - Deoghar - View & Read

• 1)

Structure of a mixed oxide is cubic close-packed(c.c.p) The cubic unit cell of mixed oxide is composed of oxide ions.One fourth of the tetrahedral voids are occupied by divalent metal A and the octahedral voids are occupied by a monovalent metal B.The formula of the oxide is:

• 2)

Solution A contains 7 g/L MgCI2 and solution B contains 7 g/L of NaCI. At room temperature, the osmotic pressure of

• 3)

In the lead-acid battery during charging, the cathode reaction is

• 4)

According to Maxwell Boltzmann distribution of energy, ....... .

• 5)

Which of the following result the chemist must have observed about his studies with KCI solution ?

#### 12th Standard CBSE Chemistry Public Model Question Paper IV 2019 - 2020 - by Archana Singh - Deoghar - View & Read

• 1)

Which of the following defects id is also known as dislocation defect?

• 2)

The density (in g mL-1) of a 3.60 M sulphuric acid solution that is 29% H2SO4 (Molar mass = 98 g mol-1) by mass will be

• 3)

If Zn2+ / Zn electrode is diluted 100 times, then the change in emf is

• 4)

At high pressure, the following reaction is of zero order.
2NH3  $\xrightarrow [ Platinum\quad catalyst ]{ 1130K }$ (g) N2(g) + 3H2(g)
Which of the following options are correct for this reaction ?

• 5)

Mond's process of is used for refining of

#### 12th Standard CBSE Chemistry Public Model Question Paper III 2019 - 2020 - by Archana Singh - Deoghar - View & Read

• 1)

KCl crystallises in the same type of lattice as does NaCl.Given that rNa+/rCl-=0.55 and rK+/rCl-=0.74.Calculate the side of the unit cell of KCl to that of NaCl

• 2)

The osmotic pressure of 0.1 M aqueous solution of NaCl is ................ Osmotic pressure of 0.1 M aqueous solution of glucose

• 3)

The metal that cannot be obtained by electrolysis of an aqueous solution of its salt is

• 4)

A relation P $\longrightarrow$ Q is completed 25 % in 25 min 50 % completed in 25 min if [P] is halved, 25% completed in 50 min if [P] is doubled. The order of reaction is

• 5)

Brine solution on electrolysis will give

#### 12th Standard CBSE Chemistry Public Model Question Paper II 2019 - 2020 - by Archana Singh - Deoghar - View & Read

• 1)

If the position of Na+ and Cl- are interchanged in NaCl having fcc arrangement of Cl ions then in the unit cell of Nacl - ions then in the unit cell of Nacl

• 2)

Two liquids X and Y form an ideal solution. The mixture has a vapour pressure of 400 mm at 300 K when mixed in the molar ratio of 1:1 and a vapour pressure of 350 mm when mixed in the molar ratio of 1:2 at the same temperature. The vapour pressures of the pure liquids X and Y respectively are

• 3)

The equivalent conductance of NaCl at concentration C and at infinite dilution are ${ \lambda }_{ c }$ and ${ \lambda }_{ \infty }$ respectively. The correct relationship between ${ \lambda }_{ c }$ and ${ \lambda }_{ \infty }$ is given by (where the constant B is positive)

• 4)

A chemical reaction was carried out at 300 K and 280 K the rate constants were found to be K1 and K2 respectively. Then

• 5)

Bauxite ore is made up Al2O3 +SiO2+TiO2+Fe2O3.This ore treated with conc.NaOH solution at 500K and 35 bar pressure for few hours and filtered hot.In the filtrate ,the species present are:

#### 12th Standard CBSE Chemistry Public Model Question Paper I 2019 - 2020 - by Archana Singh - Deoghar - View & Read

• 1)

KCl crystallises in the same type of lattice as does NaCl.Given that rNa+/rCl-=0.55 and rK+/rCl-=0.74.Calculate the side of the unit cell of KCl to that of NaCl

• 2)

Which of them is not equal to zero for an ideal solution ?

• 3)

The reaction taking place in the cell

Pt  | H2 (g) |  HCl (1.0 M) | AgCl | Ag is 1 atm

• 4)

The role of a catalyst is to change .............. .

• 5)

$\underset{\text { Impure }}{\mathrm{Ni}}+4 \mathrm{CO} \stackrel{330-350 \mathrm{~K}}{\longrightarrow} \mathrm{Ni}(\mathrm{CO})_{4}$
$\mathrm{Ni}(\mathrm{CO})_{4} \stackrel{450-470 \mathrm{~K}}{\longrightarrow} \underset{\text { Pure }}{\mathrm{Ni}}+4 \mathrm{CO}$
The above reactions are of the purification of Ni by

#### 12th CBSE Chemistry - Public Model Question Paper 2019 - 2020 - by Archana Singh - Deoghar - View & Read

• 1)

In which pair most efficient packing packing is present?

• 2)

A hypothetical reaction, A2 + B2 $\longrightarrow$ 2 AB, follows the mechanism as given below :

A2 $\rightleftharpoons$ A + A

A + B2 $\longrightarrow$ AB + B

A + B $\longrightarrow$ AB

The overall order of reaction is

• 3)

In the froth floatation process for benefaction of the ores,the ore particles float because

• 4)

Al2 O3 is reduced by electrolysis at low potentials and high currents. If 4.0 x 104 amperes of current is passed through molten Al2 O3 for 6 hours, what mass of aluminium is produced ? (Assume 100% current efficiency. At. mass of Al = 27 g mol-1).

• 5)

Which of the following are amphoteric oxides ?

${ Mn }_{ 2 }{ O }_{ 7 },{ CrO }_{ 3 },{ Cr }_{ 2 }{ O }_{ 3 },CrO,{ V }_{ 2 }{ O }_{ 5 },{ V }_{ 2 }{ O }_{ 4 }$

#### CBSE 12th Chemistry - Chemistry in Everyday Life Model Question Paper - by Archana Singh - Deoghar - View & Read

• 1)

Birth control pills contain a mixture of

• 2)

Which of the following is not a broad spectrum antibiotic ?

• 3)

A narrow spectrum antibiotic is active against ........... .

• 4)

Which of the following enhances lathering property of soap ?

• 5)

Glycerol is added to soap. It functions ........... .

#### CBSE 12th Chemistry - Biomolecules Model Question Paper - by Archana Singh - Deoghar - View & Read

• 1)

Which of the following is incorrect for glucose?

• 2)

The term anomer of glucose refers to

• 3)

Which of the following disaccharide gives a ketose and an aldose only on hydrolysis?

• 4)

The amino acids are the product of the digestion of

• 5)

#### CBSE 12th Chemistry - Organic Compounds Containing Nitrogen Model Question Paper - by Archana Singh - Deoghar - View & Read

• 1)

Amine that cannot be prepared by Gabriel phthalimide synthesis is

• 2)

Choose the incorrect statement

• 3)

The amine that reacts with NaNO2+ HCI to give yellow oily liquid is

• 4)

When aniline is heated with conc.H2SO4 at 455-475 K, it forms:

• 5)

In the following reaction, X is $X\overset { Bromination }{ \longrightarrow } Y\overset { NaNO_{ 2 }\quad /HCI }{ \longrightarrow } Z\overset { Boiling }{ \underset { { C }_{ 2 }{ H }_{ 5 }OH }{ \longrightarrow } } Tribromobenzene$

#### CBSE 12th Chemistry - Aldehydes , Ketones and Carboxylic Acids Model Question Paper - by Archana Singh - Deoghar - View & Read

• 1)

In a reaction, RCHO is reduced to RCH3 using amalgamated zinc and concentrated HCl and warming the solution. The reaction is known as

• 2)

Which of the following organic compounds answers both iodoform test and Fehling's test ?

• 3)

The product formed in Aldol condensation is

• 4)

One mole of a symmetrical alkene on ozonolysis gives two moles of an aldehyde having a molecular mass of 44 u. The alkene is

• 5)

Which of the following is the industrial method of preparation of acetaldeyde ?

#### CBSE 12th Chemistry - Alcohols , Phenols and Ethers Model Question Paper - by Archana Singh - Deoghar - View & Read

• 1)

Which of the following will produce only one product on reduction with LiAIH4?

• 2)

Phenol reacts with bromine in CS2 to give

• 3)

Among the alkenes which one produces tertiary butyl alcohol on hydration?

• 4)

Cyclohexene is best prepared from cyclohexanol by which of the following reagents:

• 5)

From amongst the following alcohols,the one that would react fastest with Conc.HCl and anhydrous ZnCl2 ,is

#### CBSE 12th Chemistry - Haloalkanes and Haloarenes Model Question Paper - by Archana Singh - Deoghar - View & Read

• 1)

A compound is formed by substitution of two chlorine for two hydrogens in propane. The number of possible isomeric compound is

• 2)

Which of the following possesses highest melting point?

• 3)

Which of the following are arranged in the decreasing order of dipole moment?

• 4)

Which of the following is not chiral?

• 5)

In the addition of HBr to propene in the absence of peroxides, the first step involves the addition of

#### CBSE 12th Chemistry - Coordination Compounds Model Question Paper - by Archana Singh - Deoghar - View & Read

• 1)

The ionization isomer of [Cr(H2O)4Cl(NO2)]Cl is

• 2)

The hybridisation of Fe in K4[Fe(CN)6] is

• 3)

Which of the following is an outer orbital complex?

• 4)

Which of the following is not considered as an organometallic compound?

• 5)

2 : 4 Dinitrophenyl hydrazine is an example for

#### CBSE 12th Chemistry - Polymers Model Question Paper - by Archana Singh - Deoghar - View & Read

• 1)

Which of the following is a linear polymer?

• 2)

Given the polymers: A=Nylon ; B=Buna-S; C=Polythene. Arrange these in increasing order of their intermolecular forces (Lower to higher)

• 3)

Which of the following is not a semisynthetic polymer?

cis-Polyisoprene Cellulose nitrate Cellulose acetate Vulcanised rubber

• 4)

Which of the following polymers are condensation polymers?

• 5)

Among cellulose,poly(vinyl chloride),nylon and natural rubber,the polymer in which the intermolecular force of attraction is weakest is

#### CBSE 12th Chemistry - The d- and f- Block Elements Model Question Paper - by Archana Singh - Deoghar - View & Read

• 1)

Which of the following is not a transition element ?

• 2)

The maximum oxidation state of osmium is

• 3)

Which of the following ion is colourless in aqueous solution ?

• 4)

Which metal has highest density ?

• 5)

Permanent magnets are generally made of alloys of

#### CBSE 12th Chemistry - The p-Block Elements Model Question Paper - by Archana Singh - Deoghar - View & Read

• 1)

Which of the following on heating does not give nitrogen gas?

• 2)

Which one of the following arrangements represents the correct order of electron gain enthalpy (with negative sign) of the given atomic species?

• 3)

The formation of O2+[PtF6]is the basis for the formation of xenon fluorides. This is because

• 4)

Affinity for hydrogen decreases in the group from fluorine to iodine. Which of the halogen acids should have highest bond dissociation enthalpy?

• 5)

Which of the following elements does not show allotropy?

#### CBSE 12th Chemistry - General Principles and Processes of Isolation of Elements Model Question Paper - by Archana Singh - Deoghar - View & Read

• 1)

The salt which is least likely to be found in minerals

• 2)

Ore dressing of iron ore is done by

• 3)

For which of the following ores,froth floatation process is applicable?

• 4)

Which of the following benefaction processes is used for the mineral,Al2O3.2H2O?

• 5)

Heating pyrites to remove sulphur is called

#### CBSE 12th Chemistry - Surface Chemistry Model Question Paper - by Archana Singh - Deoghar - View & Read

• 1)

The most adsorbed gas on activated charcoal is

• 2)

Which of the following is correct about lyophilic sols?

• 3)

The function of gum arabic in the preparation of Indian ink is

• 4)

Which of the following are the characteristics of chemisorption ?

2. Irreversibility

3. Low activation energy

Select the correct answer using the code given below :

• 5)

Which of the following relation is correct ?

(i) x/m = constant at high pressure

(ii) x/m = constant xp1/n (at intermediate pressure)

(iii) x/m = constant xpn (at lower pressure)

#### CBSE 12th Chemistry - Chemical Kinetics Model Question Paper - by Archana Singh - Deoghar - View & Read

• 1)

Rate constant of a reaction (k) is 175 litre2 mol-2 sec-1. What is the order of reaction?

• 2)

75% of the first order reaction was completed in 32 min. 50% of the reaction was completed in

• 3)

The half-life period of a radioactive element is 20 days. What will be the remaining mass of 100 g of it after 60 days?

• 4)

For a complex reaction ............. .

• 5)

Which of the following statements are in accordance with the Arhenius equation ?

#### CBSE 12th Chemistry - Electrochemistry Model Question Paper - by Archana Singh - Deoghar - View & Read

• 1)

The time required to liberate one gram equivalent of an element by passing one ampere current through its solution is

• 2)

Which has the highest oxidizing power ?

• 3)

For the reduction of silver ions with copper metal, the standard cell potential was found to be + 0.46 V at 25°C. The value of standard Gibbs energy, ${ \Delta G }^{ ° }$ will be (F = 96500 C mol-1)

• 4)

Using the data given below find out the strongest reducing agent.

${ E }_{ { Cr }_{ 2 }{ O }_{ 7 }^{ 2- }/{ Cr }^{ 3+ } }^{ \circleddash }=1.33V\quad ,\quad { E }_{ { Cl }_{ 2 }/{ Cl }^{ - } }^{ \circleddash }=1.36V$

${ E }_{ { MnO }_{ 4 }^{ - }/{ Mn }^{ 2+ } }^{ \circleddash }=1.51V\quad ,\quad { E }_{ { Cr }^{ 3+ }/{ Cr } }^{ \circleddash }=-0.74V$

• 5)

One faraday of electricity is passed thorugh molten Al2 O3 , aqueous solution of CuSO4 and molten NaCl taken in three different electrolytic cells connected in series. The mole ratio of Al, Cu and Na deposited at the respective cathode is

#### CBSE 12th Chemistry - Solution Model Question Paper - by Archana Singh - Deoghar - View & Read

• 1)

200 mL of water is added to 500mL of 0.2 M solution. What is the molarity of the dilluted solution ?

• 2)

Which one of the following gases has the lowest value of the Henry's law constant ?

• 3)

The system that forms maximum boiling azeotrope is

• 4)

If an aqueous solution of glucose is allowed to freeze, then crystals of which will be separated out first ?

• 5)

If sodium sulphate is considered to be completely dissociated into cations and anions in aqueous solution, the change in freezing point of water $(\Delta { T }_{ f })$, when 0.01 mol of sodium sulphate is dissolved in 1 kg of water, is (Kf=1.86 K kg mol-1).

#### 12th Standard CBSE Chemistry - The Solid State Model Question Paper - by Archana Singh - Deoghar - View & Read

• 1)

Wax is an example of

• 2)

In a compound, atoms of element Y form ccp lattice and those of element X occupy 2/3rd of tetrahedral voids. The formula of the compound will be

• 3)

In a solid lattice, the cation has left a lattice site and is located at an interstitial position. The lattice defect is

• 4)

In a face-centered cubic lattice, atom A occupies the corner positions and atom B occupies the face centre positions.If one atom of B is missing from one of the face centred points,the formula of the compound is

• 5)

In a solid 'AB' having NaCl structure, 'A' atoms occupy the corners of the cubic unit cell.If all the face-centred atoms along one of the axes are removed,then the resultant stoichiometry of the solid is

#### CBSE 12th Chemistry - Full Syllabus One Mark Question Paper with Answer Key - by Archana Singh - Deoghar - View & Read

• 1)

The property of crystalline solid is not

• 2)

The crystal with metal deficiency defect is

• 3)

Which of the following is not a characteristic of a crystalline solid?

• 4)

Which of the following is true about the value of refractive index of Quartz glass?

• 5)

KCl crystallises in the same type of lattice as does NaCl.Given that rNa+/rCl-=0.55 and rK+/rCl-=0.74.Calculate the side of the unit cell of KCl to that of NaCl

#### CBSE 12th Chemistry - Full Syllabus Five Marks Questions - by Archana Singh - Deoghar - View & Read

• 1)

Compounds having general molecular formula  $AFe_{ 2 }O_{ 4 }$ are called ferrites and posses spinel type structures. Some common examples are $MgFe_{ 2 }O_{ 4 }$  and $ZnFe_{ 2 }O_{ 4 }$ They may be thought of being formed by replacing $Fe^{ 2+ }$ ions present in $Fe_{ 3 }O_{ 4 }$ by bivalent cations such as $Mg^{ 2+ },Zn^{ 2+ }$ ions etc. Now answer the following questions :
(i) What types of materials are ferrites?
(ii) What are the main uses of ferrites?

• 2)

(a)  Differentiate between molarity and molality for a solution. How does a change in temperature influence their values?
(b) Calculate the freezing point of an aqueous solution containing 10.50 g of MgBr2 = 184 g) (K f for water 1.86 K kg mol-1)

• 3)

Using the standard electrode potentials (Refer Table 3.1 NCERT), predict if the reaction between the following is feasible:

(i) Fe3+(aq) and I-(aq)

(ii) Ag+(aq) and Cu(s)

(iii) Fe3+(aq) and Br-(aq)

(iv) Ag(s) and Fe3+(aq)

(v) Br2(aq) and Fe2+(aq)

• 4)

Mira's house had a fencing of iron rods. Her father suggested getting it painted. But she and her mother thought it was a waste of time and money as iron rods are strong:
(i) Whose opinion is acceptable according to you?
(ii) Give two other methods to prevent corrosion.
(iii) What is the chemical formula of rust?
(iv) Mention the values shown by Mira's father.

• 5)

(i) For the reaction A➝B, the rate of reaction becomes twenty-seven times when the concentration of A is increased three times. What is the order of the reaction?
(ii) The activation energy of a reaction is 75.2 kJ mol-1 in the absence of a catalyst and it lowers to 50.14 kJ mol-1 with a catalyst. How many times will the rate of reaction grow in the presence of a catalyst if the reaction proceeds at 25°C?

#### CBSE 12th Chemistry - Full Syllabus Three Marks Questions - by Archana Singh - Deoghar - View & Read

• 1)

Assign reasons for the following:
(i) Phosphorus doped silicon is a semiconductor.
(ii) Schottky defect lowers the density of a solid.
(iii) Some of the very old glass objects appear slightly milky instead of being transparent.

• 2)

Silver forms ccp lattice and X-ray studies of its crystals show that the edge length of its unit cell is 408.6 pm. Calculate the density of silver (Atomic mass=107.9 u)

• 3)

Conc. H2SO4 has a density of 1.9 gmL-1 and is 99 % by weight. calculate the molarity of is 99% by weight. Calculate the molarity of H2SO4 (Mol . Wt pf H2SO4 = 98 g mol-1).

• 4)

A 5% solution of cane-sugar (m.wt. = 342) is isotonic with 0.877% solution of urea. Find the molecular weight of urea.

• 5)

What is a nickel-cadmium cell? State its one merit and one demerit over lead storage cell. Write the overall reaction that occurs during discharging of this cell.

#### CBSE 12th Chemistry - Full Syllabus Two Marks Questions - by Archana Singh - Deoghar - View & Read

• 1)

Niobium crystallise in body-cetred cubic structure. If density is 8.55 g cm-3, calculate atomic radius of niobium using its atomic mass 93 u.

• 2)

Calculate the amount of benzoic acid (C6H5COOH) required  for preparing 250 ml of 0.15 M solution in methanol.

• 3)

5 g of a compound was dissolved in 100 g of water at 303 K. The vapour pressure of the solution was found to be 4.16 kilopascal. If the vapour pressure of pure water is 4.24 kPa at this temperature, what is the molecular mass of the compound?

• 4)

V1 cc of solution having molarity M1 is diluted to have molarity M2. Derive expression (in terms of M1,M2 and V1) for the volume of water required to be added.

#### CBSE 12th Chemistry - Chemical Kinetics Problems Questions - by Archana Singh - Deoghar - View & Read

• 1)

(a) Express clearly what you understand by 'rate expression' and 'rate constant' of a reaction.

(b) Nitrogen pentoxide decomposes according to the equation

2N2O5(g) $\to$ 4 NO2 (g) + O2 (g)

This first order reaction was allowed to proceed at 40oC and the data given below were collected:

 [N2O5] (M) Time (min) 0.400 0.00 0.289 20.00 0.209 40.00 0.151 60.00 0.109 80.00

(i) Calculate the rate constant for the reaction.  Include units with you answer.
(ii) Calculate the initial rate of reaction.
(iii) After how many minutes will [N2O5] be equal to 0.350 M?

• 2)

The half time of first order decomposition of nitramide is 2.1 hour at 15oC. NH2NO2(aq) $\longrightarrow$ N2O(g) + H2O (I)
If 6.2 g of MH2NO2 is allowed to decompose, calculate (i) time taken for NH2NO2 to decompose 99% and (ii) volume of dry N2O produced at this point, measured at STP.

• 3)

The time required for 10% completion of a first order reaction at 298 K is equal to that required for its 25% completion at 318 K. If the pre-exponential factor for the reaction is 3.56 $\times 10 ^{9} s^{-1}$, calculate its rate constant at 318 K and also the energy of activation.

• 4)

For the reaction, N2O5(g) = 2 NO2(g) + 0.5 O2 (g), calculate the mole fraction of N2O5 (g) decomposed at a constant volume and temperature, if the initial presure is 600 mm Hg and the pressure at any time is 960 mm Hg. Assume ideal gas behaviour.

• 5)

At constant temperature and volume, X decomposes as 2 X (g) $\longrightarrow$  3 Y (g) + 2 Z (g). Px is the partial pressure of X.

Observation No. Time (in minutes) Px (in mm of Hg)
1 0 800
2 100 400
3 200 200

(i) What is the order of reaction with respect to X ?  (ii) Find the time for 75% completion of the reaction. (iii) Find the total pressure when pressure of X is 700 mm of Hg.

#### CBSE 12th Chemistry - Electrochemistry Problems Questions - by Archana Singh - Deoghar - View & Read

• 1)

Solutions of two electrolytes 'A' and 'B' are diluted. The ${ \Lambda }_{ m }$ of 'B' increases 1.5 times while that of 'A' increases 25 times. Which of the two is a strong electrolyte? Justify your answer.

• 2)

The standard electrode potential ($E°$)for Daniell cell is +1.1 V. Calculate the $\Delta G°$ for the reaction.
Zn(s)+Cu2+(aq)$\rightarrow$Zn2+(aq)+Cu(s)

• 3)

The standard electrode potential for Daniel cell is 1.1 V. Calculate the standard Gibbs energy for the cell reaction.

• 4)

(a) Calculate $\Delta G°$for the reaction Mg(s)+Cu2+$\rightarrow$Mg2+(aq)+Cu(s)
Given: ${ E }_{ cell }^{ ° }$=+2.7V, 1F=96500 C mol-1
(b) Name the type of cell which was used in Apollo space programme for providing electrical power.

• 5)

Conductivity of $2.5\times { 10 }^{ -4 }$M methanoic acid is $5.25\times { 10 }^{ -5 }S{ cm }^{ -1 }$
Calculate its molar conductivity and degree of dissociation.

#### CBSE 12th Chemistry - Solution Problems Questions - by Archana Singh - Deoghar - View & Read

• 1)

45 g of ethylene glycol (C2H4O2) is mixed with 600 g of water. Calculate
(i) the freezing point depression and
(ii) the freezing point of the solution.

• 2)

Calculate the boiling point of solution when 4 g of MgSO4 (M = 120 g mol-1) was dissolved in 100 g of water, assuming MgSO4 undergoes complete ionization. (Kb for water = 0.52 K kg mol-1)

• 3)

A 5 percent solution (by mass) of cane-sugar (M.W. 342) is isotonic with 0.877% solution of substance X. Find the molecular weight of X.

• 4)

Calculate the boiling point of a 1M aqueous solution (density 1.04 g mL-1) of potassium chloride (Kb for water = 0.52 K kg mol-1, Atomic masses : K = 39 u, CI = 35.5 u). Assume, potassium chloride is completely dissociated in solution.

• 5)

At 10$°$ C, the average osmotic pressure of blood is 8.8 atm. Find the total concentration of the various constituents in the blood. Assuming that the concentration is the same as the molarity, find the freezing point of the solution (Kf for water = 1.86 K kg mol-1)

#### CBSE 12th Chemistry - The Solid State Problem Questions - by Archana Singh - Deoghar - View & Read

• 1)

With the help of a labelled diagram show that there are four octahedral voids per unit cell in cubic close packed structure.

• 2)

Show that in cubic packed structure, eight tatrahedral voids are persent per unit cell.

• 3)

Lithium borohydride,LiBH4,crystallize in an orthorhombic system with 4 molecules per unit cell.The unit cell dimensions are: a=6.81$\overset { 0 }{ A }$ ,b=4.43$\overset{0}{A}$ and c=7.17$​​\overset{0}{A}$.Calculate the density of the crystal.Take atomic mass of Li=7,B=11 and H=1 a.m.u.

• 4)

If silver iodide crystallizes in a zinc blende structure with I-ions forming the lattice,then calculate fraction of the tetrahedral voids occupied by Ag+ ions

• 5)

A compound consisting of the monovalent ions A+,B- crystallizes in the body-centred cubic lattice.(i)What is the of the compound? (ii)If one one of A+ions  from the corner is replaced by a monovalent ion C+,what would be the simplest formula of the resulting compound?

#### 12th CBSE Chemistry - Chemistry in Everyday Life Five Marks Model Question Paper - by Sudha George - Kochi - View & Read

• 1)

Due to hectic and busy schedule, Mr. Singh started taking junk food in the lunch break and slowly became habitual of eating food irregularly to excel in his field. One day during meeting he felt severe chest pain and fell down. Mr. Khanna, a close friend of Mr. Singh took him to doctor immediately. The doctor diagnosed that Mr. Singh was suffering from acidity and prescribed some medicines. Mr. Khanna advised him to eat home made food and change his lifestyle by doing yoga, meditation and some physical exercise. Mr. Singh followed his friend's advice and after few days he started feeling bener.
(i) What are the values (at least two) displayed by Mr. Khanna?
(ii)What are antacids? Give one example.
(iiii)Would it be advisable to take antacids for a long period of time? Give reason

• 2)

Due to hectic and busy schedule, Mr. Angad made his life full of tensions and anxiety. He started taking sleeping pills to overcome the depression without consulting the doctor. Mr. Deepak, a close friend of Mr. Angad, advised him to stop taking sleeping pills and and suggested to change his lifestyle by doing yoga, meditation and some physical exercise. Mr. Angad followed his friend's advice and after few days he started feeling better. After rearing the above passage, answer the following:
(i) What are the values (at least two) displayed by Mr. Deepak?
(ii) Why is it not advisable to take sleeping pills without consulting doctor?
(iii) What are tranquilizers? Give two examples.

• 3)

Ramesh went to a department store to purchase groceries, On one of shelves he noticed sugar-free tablets, He decided to buy them for his grandfather who was a diabetic. There was three types of sugar-free tablets, Ramesh decided to buy sucralose which was good for his grandfather's health.
(i) Name another sugar-free tablet which Ramesh did not buy,
(ii) Was it right to purchase such medicines without doctor's prescription?
(iii)Wha is quality of Ramesh is reflected above?

• 4)

Mr. Roy, the principal of one reputed school organized a seminar in which he invited parents and principals to discuss the serious issue of diabetes and depression in students. They all resolved this issue by strictly banning the junk food in schools and to introduce healthy snacks and drinks like soup, lassi, milk etc. in school canteens. They also decided to make compulsory half an hour physical activities for the students in the morning assembly daily. After six months, Mr. Royconducted the health survey in most of the schools and discovered a tremendous improvement in the health of students.
(i)What are the values (at least two) displayed by Mr.Roy?
(iii) What are tranquillizers? Give an example.
(iv)Why is use of aspartame limited to cold foods and drinks?

• 5)

On the occasion of world health day, Dr. Satpal organized a 'Health Camp' for poor farmers living in a near village. After check up, he was shocked to see the most of the farmers suffered from cancer due to regular exposure to pesticides and many were diabetic. They distributed free medicines to them. Dr. Satpal immediately reported the matter to the National Human Right Commission (NHRC). On the suggestion of NHRC, the government decided to provide medical care, financial assistance, setting up of super-speciality hospitals for treatment and prevention of the deadly disease in the affected villages all over India.
(i) Write the values shown by :
(a) Dr. Satpal
(b) NHRC
(ii) What type of analgesics are chiefly used for the relief of pains of terminal cancer?
(iii) Give an example of artificial sweetener that could have been recommended to diabetic patients.

#### CBSE 12th Standard Chemistry - Polymers Five Marks Model Question Paper - by Sudha George - Kochi - View & Read

• 1)

Identify the monomers in following Polymeric structures.
a.
b. (- NH - CO - NH - CH2 -)2

• 2)

i.Which material is used as substitute for wool in making commercial fibers as orlon or acrilan?
ii.What are the conditions required for preparation of High density polythene.
iii. Name and give the preparation of the polymer used for making unbreakable crockery.

• 3)

What is nylon?Write an equation for the chemistry involved contain alternate monomers of each type.What is the weight percent of ethylene in this copolymer.

• 4)

Study the given passage carefully and answer the questions that follow:
Shalini studied a chapter on Polymers in school and came across the following paragraph: The durability, strength, low cost, water and chemicals resistance, welding properties, lesser'. energy, fewer atmosphere emissions and light weight are advantages of plastic bags. Shalini is confused as she has been reading in the
newspaper about the ban on the usage of plastic substances. She further finds that despite the durability, the use of these materials has presented mankind with serious waste disposal problem as these materials do not disintegrate by themselves. In view of this, certain polymers are being developed which are broken down rapidly by micro-organisms. Shalini feels relaxed that such kinds of biomaterials are being developed.
(i) Name the class of these useful polymers which do not harm the environment.
(ii) Give anyone example of these polymers and name its monomers.
(iii) Comment on the qualities of Shalini.

• 5)

After the ban on plastic bags, students of a school decided to make people aware of the harmful effects of plastic bags on the environment and Yamuna River. To make the awareness more impactful, they organised a rally by partnering with other schools and distributed paper bags to vegetable vendors, shopkeepers and departmental stores. All the students pledged not to use polythene bags in the future to save the Yamuna River.
(i) What values are shown by the students?
(ii) What are bio-degradable polymers ? Give one example.
(iii) Is polyethene a condensation or an addition polymer?

#### 12th CBSE Chemistry - Biomolecules Five Marks Model Question Paper - by Sudha George - Kochi - View & Read

• 1)

How do expimers differ from anomers ?

• 2)

Give reason for the following :

(i) On electrolysis in acidic solution, aminoacids migrate towards cathode while in alkaline solution these migrate towards anode.

(ii) The mononamino monocarboxylic acids have two pK values.

• 3)

What forces are responsible for the stability of $\alpha$ - helix ? Why is it named as 3.613 helix?

• 4)

The Ka and Kb values of $\alpha$ - amino acids are very low. Explain.

• 5)

Write the structure of alanine at pH = 2 and pH = 10.

#### 12th Standard CBSE Chemistry - Organic Compounds Containing Nitrogen ( Amines ) Five Marks Model Question Paper - by Sudha George - Kochi - View & Read

• 1)

How will you convert toluene into sym-trinitrobenzene?

• 2)

Why is an amide more acidic than amine?

• 3)

Why does bromination of aniline, even under very mild conditions, gives 2, 4, 6-tribromoaniline instantaneously?

• 4)

(a) Write the structures of main products when aniline reacts with the following reagents:
(i) Br2 water
(ii) HCI
(iii) (CH3CO)2O / pyridine
(b) Arrange the following in the increasing order of their boiling point:
C2H5NH2 , C2H5OH, (CH3)3N
(c) Give a simple chemical test to distinguish between the following pair of compounds:
(CH3)2NH and (CH3)3N

• 5)

(a) Write the structures of main products when products when benzene diazonium chloride reacts with the following reagents:
(i) H3PO2+H2O
(ii) CuCN/KCN
(iii) H2O
(b) Arrange the following in the increasing order of their basic character in an aqueous solution:
C2H5NH2 , (C2H5)2NH, (C2H5)3N
(c) Give a simple chemical test to distinguish between the following pair of compounds:
C6H5-NH2 and C6H5-NH-CH3

#### 12th Standard CBSE Chemistry - Aldehydes , Ketones and Carboxylic Acids Five Marks Model Question Paper - by Sudha George - Kochi - View & Read

• 1)

(a) Describe the following giving linked chemical equations:
(i) Cannizzaro reaction
(ii) Decarboxylation
(b) Complete the following chemical equations:

(iii) $C_6H_5CONH_2 \xrightarrow [heat] {H_3O^+}$

• 2)

(a) Identify A, B and C in the following sequence of reactions:

(b) Predict the structures of the products formed when benzaldehyde is treated with
(i) conc. NaOH
(ii) HNO3 / H2SO4 (at 273 - 383 k)

• 3)

(a) Explain the mechanism of nucleophilic attack on the carbonyl group of an aldehyde or a ketone.
(b) An organic compound (A) (molecular formula C8H16O2) was hydrolysed with dilute sulphuric acid to give a carboxylic acid (B) and an alcohol (C).  Oxidation of (C) with chromic acid also produced (B).  On dehydration (C) gives but-1-ene.  Write the equations for the  reactions involved.

• 4)

(a) Illustrate the following name reactions:
(i) Hell-Volhard-Zelinsky reaction
(ii) Woff-Kishner reduction reaction
(b) How are the following conversions carried out:
(i) Ethylcyanide to ethanoic acid
(ii) Butan-1-ol to butanoic acid
(iii) Methylbenzene to benzoic acid Write chemical equations for the involved reactions.

• 5)

An organic compound (A) on treatment with ethyl alcohol gives a carboxylic acid (B) and compound (C).  Hydrolysis of (C) under acidified conditions gives (B) and (D).  Oxidation of (D) with KMnO4 also gives (B).  (B) on healting with Ca(OH)2 gives (E) having molecular formula C3H6O.  (E) does not give Tollen's test and does not reduce Fehling's solution but forms a 2, 4-dinitrophenylhydrazone.  Identify (A), (B), (C), (D) and (E).

#### 12th Standard CBSE Chemistry - Alcohols , Phenols and Ethers Five Marks Model Question Paper - by Sudha George - Kochi - View & Read

• 1)

PCl5 reacts with ethanol to form chloromethane.However, with phenol, it does not give chlorobenzene but gives triphenylphosphate.Explain.

• 2)

Explain why alcohols do not react with NaBr but H2SO4 is added they form alkyl bromides.

• 3)

Although both allyl alcohol and 1-propanol are primary alcohols,they can still be distinguished by Lucas reagent.Explain how?

• 4)

2,2-Dimethyloxirane can be cleaved by acid (H+).Write its mechanism.

• 5)

Miss Usha was asked to synthesize alcohol by acidic hydration of 'l-butene. She was unaware of the fact that the vessel she used had some coating of a  metal, and in addition to alcohol, compound X was I isolated X forms bisulphate compound as well as 2, 4-dinitrophenylhydrazone. Separation of alcohol could be made by physical as well as by chemical methods.
(i) How are alcohol and Xformed?
(ii) Can alcohol and Xgive iodoform test?
(iii) Give different methods of separation?
(iv) What value did Miss. Usha lack?

#### 12th Standard CBSE Chemistry - Alcohols , Phenols and Ethers Five Marks Questions - by Archana Singh - Deoghar - View & Read

• 1)

PCl5 reacts with ethanol to form chloromethane.However, with phenol, it does not give chlorobenzene but gives triphenylphosphate.Explain.

• 2)

Explain why alcohols do not react with NaBr but H2SO4 is added they form alkyl bromides.

• 3)

Although both allyl alcohol and 1-propanol are primary alcohols,they can still be distinguished by Lucas reagent.Explain how?

• 4)

Gasoline is being used worldwide for running automobile, aeroplane etc. Due to the presence of nitrogen and sulphuric compounds in gasoline, the exhaust gases contain oxides of nitrogen and sulphur which are major pollutants in the environment in contrast, ethanol is a much cleaner fuel because it produces only CO2 and Hp. Now answer the following questions:
(a) Besides being a cleaner fuel, what are the other advantages of using ethanol as a fuel in automobile?
(b) What are the disadvantages of using ethanol as a fuel? What are the value associated with its use?

• 5)

Miss Usha was asked to synthesize alcohol by acidic hydration of 'l-butene. She was unaware of the fact that the vessel she used had some coating of a  metal, and in addition to alcohol, compound X was I isolated X forms bisulphate compound as well as 2, 4-dinitrophenylhydrazone. Separation of alcohol could be made by physical as well as by chemical methods.
(i) How are alcohol and Xformed?
(ii) Can alcohol and Xgive iodoform test?
(iii) Give different methods of separation?
(iv) What value did Miss. Usha lack?

#### 12th Standard CBSE Chemistry - Organic Compounds Containing Nitrogen Five Marks Questions - by Archana Singh - Deoghar - View & Read

• 1)

Illustrate the following reactions giving a chemical equation in each case:
(i) Gabriel phthalimide synthesis
(ii) A coupling reaction.
(iii) Hoffmann's bromamide reaction.

• 2)

Give one chemical test each to distinguish between the compounds in the following pairs:
(i) Methyleamine and dimethylamine
(ii) Aniline and benzylamine
(iii) Ethylamine and aniline

• 3)

How would you achieve the following conversions?
(i) Nitrobenzene to aniline
(ii) An alkyl halide to a quaternary ammonium salt.
(iii) Aniline to benzonitrile. Write the chemical equation with reaction conditions in each case.

• 4)

A compound 'X' having molecular formula C3H7NO, reacts with Br2 in presence of KOH to give another compound 'Y'. The compound Y reacts with NHO2 to form ethanol and N2 gas. Identify the compounds X and Y and write the reactions involved.

• 5)

An aliphatic compound 'A' with molecular formula C2H3Cl on treatment with AgCN hives two isomeric compounds of unequal amounts with the molecular formula C3H3N. The minor of nthese two products on complete reduction with Hin the presence of Ni gives a compound 'B' with  molecular formula C3H9N. Identify the compounds 'A' , 'B' and write the reactions involved.

#### CBSE 12th Chemistry - Biomolecules Five Marks Questions - by Archana Singh - Deoghar - View & Read

• 1)

How do expimers differ from anomers ?

• 2)

Glucose and fructose give the same osazone ? Explain.

• 3)

Give reason for the following :

(i) On electrolysis in acidic solution, aminoacids migrate towards cathode while in alkaline solution these migrate towards anode.

(ii) The mononamino monocarboxylic acids have two pK values.

• 4)

What forces are responsible for the stability of $\alpha$ - helix ? Why is it named as 3.613 helix?

• 5)

The Ka and Kb values of $\alpha$ - amino acids are very low. Explain.

#### CBSE 12th Chemistry - Chemistry in Everyday Life Five Marks Questions - by Archana Singh - Deoghar - View & Read

• 1)

Due to hectic and busy schedule, Mr. Singh started taking junk food in the lunch break and slowly became habitual of eating food irregularly to excel in his field. One day during meeting he felt severe chest pain and fell down. Mr. Khanna, a close friend of Mr. Singh took him to doctor immediately. The doctor diagnosed that Mr. Singh was suffering from acidity and prescribed some medicines. Mr. Khanna advised him to eat home made food and change his lifestyle by doing yoga, meditation and some physical exercise. Mr. Singh followed his friend's advice and after few days he started feeling bener.
(i) What are the values (at least two) displayed by Mr. Khanna?
(ii)What are antacids? Give one example.
(iiii)Would it be advisable to take antacids for a long period of time? Give reason

• 2)

Due to hectic and busy schedule, Mr. Angad made his life full of tensions and anxiety. He started taking sleeping pills to overcome the depression without consulting the doctor. Mr. Deepak, a close friend of Mr. Angad, advised him to stop taking sleeping pills and and suggested to change his lifestyle by doing yoga, meditation and some physical exercise. Mr. Angad followed his friend's advice and after few days he started feeling better. After rearing the above passage, answer the following:
(i) What are the values (at least two) displayed by Mr. Deepak?
(ii) Why is it not advisable to take sleeping pills without consulting doctor?
(iii) What are tranquilizers? Give two examples.

• 3)

Ramesh went to a department store to purchase groceries, On one of shelves he noticed sugar-free tablets, He decided to buy them for his grandfather who was a diabetic. There was three types of sugar-free tablets, Ramesh decided to buy sucralose which was good for his grandfather's health.
(i) Name another sugar-free tablet which Ramesh did not buy,
(ii) Was it right to purchase such medicines without doctor's prescription?
(iii)Wha is quality of Ramesh is reflected above?

• 4)

Mr. Roy, the principal of one reputed school organized a seminar in which he invited parents and principals to discuss the serious issue of diabetes and depression in students. They all resolved this issue by strictly banning the junk food in schools and to introduce healthy snacks and drinks like soup, lassi, milk etc. in school canteens. They also decided to make compulsory half an hour physical activities for the students in the morning assembly daily. After six months, Mr. Royconducted the health survey in most of the schools and discovered a tremendous improvement in the health of students.
(i)What are the values (at least two) displayed by Mr.Roy?
(iii) What are tranquillizers? Give an example.
(iv)Why is use of aspartame limited to cold foods and drinks?

• 5)

On the occasion of world health day, Dr. Satpal organized a 'Health Camp' for poor farmers living in a near village. After check up, he was shocked to see the most of the farmers suffered from cancer due to regular exposure to pesticides and many were diabetic. They distributed free medicines to them. Dr. Satpal immediately reported the matter to the National Human Right Commission (NHRC). On the suggestion of NHRC, the government decided to provide medical care, financial assistance, setting up of super-speciality hospitals for treatment and prevention of the deadly disease in the affected villages all over India.
(i) Write the values shown by :
(a) Dr. Satpal
(b) NHRC
(ii) What type of analgesics are chiefly used for the relief of pains of terminal cancer?
(iii) Give an example of artificial sweetener that could have been recommended to diabetic patients.

#### CBSE 12th Chemistry - Aldehydes , Ketones and Carboxylic Acids Five Marks Questions - by Archana Singh - Deoghar - View & Read

• 1)

(a) Illustrate the following name reactions:
(i) Cannizzaro's reaction
(ii) Clemmensen reduction
(b) How would you obtain the following:
(i) But-2-enal from ethanal,
(ii) Butanoic acid from butanol,
(iii) Benzoic acid from ethylbenzene?

• 2)

(a) Illustrate the following name reactions:
(i) Hell-Volhard-Zelinsky reaction
(ii) Woff-Kishner reduction reaction
(b) How are the following conversions carried out:
(i) Ethylcyanide to ethanoic acid
(ii) Butan-1-ol to butanoic acid
(iii) Methylbenzene to benzoic acid Write chemical equations for the involved reactions.

• 3)

(a) How will you prepare the following compounds starting with benzene:
(i) Benzaldehyde
(ii) Acetophenone
(b) Give chemical tests to distinguish between the following pairs of compounds
(i) Ethanal and Propanal
(ii) Benzaldehyde and Acetophenone
(iii) Phenol and Benzoic acid

• 4)

(a) Explain the mechanism of nucleophilic attack on a carbonyl group of an aldehyde or a ketone.
(b) How would you bring about the following conversions:
(i) Propanone to Propene
(ii) Ethanol to 3-hydroxybutanal
(iii) Benzaldehyde to Benzophenone

• 5)

(a) Write chemical equations to illustrate the following name bearing reactions:
(i) Cannizzaro's reaction
(ii) Hell-Volhard-Zelinsky reaction
(b) Give chemical tests to distinguish between the following pairs of compounds:
(i) Propanal and Propanone
(ii) Acetophenone and Benzophenone
(iii) Phenol and Benzoic acid

#### CBSE 12th Chemistry Polymers Five Marks Questions - by Archana Singh - Deoghar - View & Read

• 1)

Low level of noradrenaline is the cause of depression. What type of drugs are needed to cure this problem? Name two drugs.

• 2)

Classify the following polymers on the basis of inter molecular forces. Justify your classification.
PVC, Nylon, Bakelite, Buna-s.

• 3)

What is nylon?Write an equation for the chemistry involved contain alternate monomers of each type.What is the weight percent of ethylene in this copolymer.

• 4)

Study the given passage carefully and answer the questions that follow:
Shalini studied a chapter on Polymers in school and came across the following paragraph: The durability, strength, low cost, water and chemicals resistance, welding properties, lesser'. energy, fewer atmosphere emissions and light weight are advantages of plastic bags. Shalini is confused as she has been reading in the
newspaper about the ban on the usage of plastic substances. She further finds that despite the durability, the use of these materials has presented mankind with serious waste disposal problem as these materials do not disintegrate by themselves. In view of this, certain polymers are being developed which are broken down rapidly by micro-organisms. Shalini feels relaxed that such kinds of biomaterials are being developed.
(i) Name the class of these useful polymers which do not harm the environment.
(ii) Give anyone example of these polymers and name its monomers.
(iii) Comment on the qualities of Shalini.

• 5)

After the ban on plastic bags, students of a school decided to make people aware of the harmful effects of plastic bags on the environment and Yamuna River. To make the awareness more impactful, they organised a rally by partnering with other schools and distributed paper bags to vegetable vendors, shopkeepers and departmental stores. All the students pledged not to use polythene bags in the future to save the Yamuna River.
(i) What values are shown by the students?
(ii) What are bio-degradable polymers ? Give one example.
(iii) Is polyethene a condensation or an addition polymer?

#### 12th Standard CBSE Chemistry - Haloalkanes and Haloarenes Five Marks Questions - by Archana Singh - Deoghar - View & Read

• 1)

Explain why alkyl halides are generally not prepared in the laboratory by free radical halogenation of alkanes.

• 2)

Explain why chorination of n-butane in presence of light at 298 K gives a mixture of 72% of 2-chlorobutane and 28 % of 1-chlorobutane.

• 3)

Wurtz reaction falils in case of tert-alkyl halides. Explain.

• 4)

Explain the following in one or two sentences
(i) Displacement of cyanic and amide ion is never observed in nucleophilic substitution reactions.
(ii) RCI is hydrolysed to ROH slowly but the reaction is rapid if a catalytic amount of KI is added to the reaction mixture.

• 5)

(R)-2- Bromooctane reacts with NaSH to form (S)-2- octanethiol with inversion of configuration at the stereocentre.How can we obtain (R)-2 octanethiol from (R)-2-bromoctane?

#### 12th Standard CBSE Chemistry - Coordination Compounds Five Marks Questions - by Archana Singh - Deoghar - View & Read

• 1)

Explain the following
i. All octahedral complexes of Ni2+ must be outer orbital complexes.
ii. NH4+ ion does not form any complex
iii. (SCN)-1 ion is involved in linkage isomerism in co-ordination compounds.

• 2)

Explain the following
i. Cu(OH)2 is soluble in ammonium hydroxide but not in sodium hydroxide solution.
ii. EDTA is used to cure lead poisoning
iii. Blue coloured solution of [CoCl4 2-] changes to pink on reaction with HgCl2.

• 3)

Using crystal field theory, draw energy level diagram, write electronic configuration of the central metal atom/ion and determine the magnetic moment value in the following :

(i) $[CoF_6]^{3-}, [Co(H_2O)_6]^{2+},[Co(CN)_6]^{3-}$

(ii) $[FeF_6]^{3-}, \ [Fe(H_2O)_6]^{2+}, [Fe(CN)_6]^{4-}$.

• 4)

Using valence bond theory, explain the following in relation to the complexes given below :

$[Mn(CN)_6]^{3-}, [Co(NH_3)_6]^{3+}, [Cr(H_2O)_6]^{3+}, [FeCl_6]^{4-}$

(i) Type of hybridisation     (ii) Inner or outer orbital complex.     (iii) Magnetic behaviour.     (iv) Spin only magnetic moment value.

• 5)

CoSO4Cl.5 NHexists in two isomeric forms 'A' and 'B' gives white precipitate with BaClbut does not react with AgNO3.  Answer the following questions.

(i) Identify 'A' and 'B' and write their structure formulas.     (ii) Name the type of isomerism involved     (iii) Give the IUPAC name of 'A' and 'B'.

#### 12th Standard CBSE Chemistry - The d- and f- Block Elements Five Marks Questions - by Archana Singh - Deoghar - View & Read

• 1)

(a) Given below are the electrode potential values, Eo for the some of the first row of transition elements:

 Element EoM2+/M (V) V(23)  Cr(24) Mn(25) Fe(26) Co(27) Ni(28) Cu(29) -1.18 -0.91 -1.18 -0.44 -0.28 -0.25 +0.34

Explain the irregularities in these values on the basis of electronic structures of atoms.

(b) Complete the following reaction equations:

(i) Cr2O72-+Sn2++H+$\longrightarrow$

(ii) MnO4-+Fe2++H+$\longrightarrow$

• 2)

Calculate the number of unpaired electrons in following gaseous ions: Mn3+, Cr3+, V3+ and Ti3+. Which one of these is the most stable in aqueous solution?

• 3)

Give example and suggest reasons for the following features of the transition metal chemistry:
(a) The lowest oxide of transition metal is basic, the highest is amphoteric acidic.
(b) A transition metal exhibits higher oxidation states in oxides and fluorides.
(c) The highest oxidation state is exhibited in oxoanions of a metal.

• 4)

Write down the number of 3d electrons in each of the following ions: Ti2+, V2+, Cr3+, Mn2+, Fe2+, Fe3+, Co2+, Ni2+ and Cu2+. Indicate how would you expect the five 3d orbitals to be occupied for these hydrated ions (octahedral).

• 5)

On the basis of Lanthanoid contraction, explain the following:

(i) NAture of bonding in La2O3 and Lu2O3.

(ii) Trends in the stability of oxo salts of lanthanoids from LA to Lu.

(iii) Stability of the comlexes of lanthanoids.

(iv) Radii of 4d and 5d block elements.

(v) trends in acidic character of lanthanoid oxides.

#### CBSE 12th Chemistry - The p-Block Elements Five Marks Questions - by Archana Singh - Deoghar - View & Read

• 1)

(a) Draw the structures of the following:

(i) N2O5

(ii) XeOF4

(b) Explain the following observations:

(i) The electron gain enthalpy of sulphur atom has a greater negative value than that of oxygen atom.

(ii) Nitrogen does not form pentahalides.

(iii) In aqueous solutions, HI is a stronger acid than HCl.

• 2)

(a) Draw the structures of the following:

(i) XeF4     (ii) H2S2O7

(b) Explain the following observations:

(i) Phosphorus has a greater tendency for catenation than nitrogen.

(ii) The negative value of electron gain enthalpy is less for fluorine than that for chlorine.

(iii) Hydrogen fluoride has a much higher boiling point than hydrogen chloride.

• 3)

(a) Explain the following:

(i) NF3 is an exothermic compound whereas NCl3 is not.

(ii) F2 is most reactive of all the four common halogens.

(b) Complete the following chemical equations:

(i) c + H2SO4 (conc.) $\to$

(ii) P4 + NaOH + H2$\to$

(iii) Cl2 $\to$ $\underset{excess}{F_2}$ $\to$

• 4)

On heating, lead (II) nitrate gives a brown gas 'A'. The gas 'A' on cooling changes to colourless solid 'B'. Solid 'B' on heating with NO changes to a blue solid 'C'. Identiy 'A', 'B' and 'C' and also write reactions involved and draw the structures of 'B' and 'C'.

• 5)

(a)Assign a reason for each of the following statements:
(i)All the bonds in $PCI_{ 5 }$are not equal in length.
(b) Write the structural formulae of the following compounds:

$(i)BrF_{ 3 }\quad (ii)XeF_{ 2 }$

#### 12th Standard CBSE Chemistry - General Principles and Processes of Isolation of Elements Five Marks Questions - by Archana Singh - Deoghar - View & Read

• 1)

Explain the following
i. Carbon reduction process is not applied for reducing aluminium oxide to aluminium.
ii. Aq Sodium chloride cannot be used for the isolation of sodium by electrolytic reduction method.
iii. Thermite process is quite useful for repairing the broken parts of machines.

• 2)

Why reduction of metal oxide easier if the metal is formed in the liquid state at the temperature of reduction?

• 3)

While washing a miner's overalls, a washer woman noticed that sand and similar dirt fell to the bottom of the wash tub. What was peculiar, the copper bearing compounds that had come to the clothes from the mines were caught in the soaplids and so they came to the top. One of her clients was a chemist, Mrs. Malik. The washer woman told her experience to Mrs. Malik. The latter thought that the idea could be used for separating copper compounds from rocky and earth materials on a large scale. After reading the above passage answer the following questions-
(i) Name the process of concentration of ore based on the observation of washer woman.
(ii) What type of ores are concentrated by this process?
(iii) What values are shown by washer woman and Mrs.Malik?

• 4)

While washing a miner's overalls, a washer woman noticed that sand and similar dirt fell to the bottom of the wash tub. What was peculiar, the copper bearing compounds that had come to the clothes from the mines were caught in the soaplids and so they came to the top. One of her clients was a chemist, Mrs. Malik. The washer woman told her experience to Mrs. Malik. The latter thought that the idea could be used for separating copper compounds from rocky and earth materials on a large scale. After reading the above passage answer the following questions-

What type of ores are concentrated by this process?

• 5)

While washing a miner's overalls, a washer woman noticed that sand and similar dirt fell to the bottom of the wash tub. What was peculiar, the copper bearing compounds that had come to the clothes from the mines were caught in the soaplids and so they came to the top. One of her clients was a chemist, Mrs. Malik. The washer woman told her experience to Mrs. Malik. The latter thought that the idea could be used for separating copper compounds from rocky and earth materials on a large scale. After reading the above passage answer the following questions-

What values are shown by washer woman and Mrs.Malik?

#### 12th Standard CBSE Chemistry - Surface Chemistry Five Marks Questions - by Archana Singh - Deoghar - View & Read

• 1)

What are the applications of adsorption in chemical analysis?

• 2)

A house wife while working in the kitchen gots a cut on the finger. It started bleeding and become panicked. She immediately called her neighbour.She had kept ferric chloride in her house. She immediately applied it on the affected area and the bleeding stopped.
(i) What is the chemical formula of ferric chloride?
(ii) Why did bleeding stop on applying it on the affected finger?
(iii) What is the name of the phenomenon involved?
(iv) What do we learn from it? What is the value associated with this from the point of view of chemist?

• 3)

Radha and Meera are fast friends. They both study in class XII.Radha is a student of science while Meera follows commerce stream. One day, when they were playing, Radha got hurt and started bleeding. Meera took her to house and applied some alum on the cut. The bleeding stopped immediately.
(i)Why bleeding stopped when some alum is applied on the cut?
(ii) What are the values associated with Meera's decision to take Radha to her house and apply alum on her cut?

• 4)

Reetu is purely vegetarian but her husband Rohit likes non-vegetarian food. He regularly buys nonvegetarian goods (fish, meet, eggs etc.) and store these in fridge. The intermixing of odours creates problem for Reetu. Their daughter Rihana is a student of science. One day Rihana suggested her mother to put some small pieces of charcoal in the fridge as she thinks that this will solve the problem to some extent.
(i) Do you think by putting some small pieces of charcoal in the fridge will solve the problem of intermixing of odours. Give reason for your answer.
(ii) What are the values associated with Rihana's suggestion?

• 5)

On visit to your native village, you find that lot of smoke, dust and some other gases are coming out of the chimney of a recently set up factory near the village.
(i) As a chemistry student, what method you will suggest the factory owner to manage dust and smoke?
(ii) What is the basic principle involved in your suggestion?

#### 12th Standard CBSE Chemistry - Chemical Kinetics Five Marks Questions - by Archana Singh - Deoghar - View & Read

• 1)

(a) Define the following:

(i) Order of a reaction

(ii) Elementary step in a reaction

(b) A first order reaction has a rate constant value of 0.00510 min-1.  If we begin with 0.10 M concentration of the reactant, how much of the reactant will remain after 3.0 hours?

• 2)

(a) Explain the following terms:

(i) Rate of a reaction

(ii) Activation energy of a reaction

(b) The decomposition of phosphine (PH3) proceeds according to the following equation:

4PH3(g) $\to$P4 (g) + 6H2 (g)

It is found that the reaction follows the following rate equation:

Rate = k [PH3]

The half-life of PH3 is 37.9 s at 120 oC.

(i) How much time is required for 3/4th of PH3 to decompose?

(ii) What fraction of the original sample of PH3 remains behind after 1 minutes?

• 3)

(a) Explain the following terms:
(i) Order of a reaction
(ii) Molecularity of a reaction
(b) The rate of a reaction increases four times when the temperature changes from 300 k to  320 K.  Calculate the energy of activation of the reaction, assuming that it does not change with temperature.
(R = 8.314 J K-1 mol-1)

• 4)

What is Arrhenius equation to describe the effect of temperature on rate of a reaction? How can it be used to calculate the activation energy of a reaction?

• 5)

Describe briefly the dependence of reaction rate of a chemical reaction on temperature. Explain the effect of temperature on the rate constant of a reaction.

#### 12th Standard CBSE Chemistry - Haloalkanes and Haloarenes Five Mark Model Question Paper - by Sudha George - Kochi - View & Read

• 1)

Explain why alkyl halides are generally not prepared in the laboratory by free radical halogenation of alkanes.

• 2)

Explain why chorination of n-butane in presence of light at 298 K gives a mixture of 72% of 2-chlorobutane and 28 % of 1-chlorobutane.

• 3)

Wurtz reaction falils in case of tert-alkyl halides. Explain.

• 4)

Explain the following in one or two sentences
(i) Displacement of cyanic and amide ion is never observed in nucleophilic substitution reactions.
(ii) RCI is hydrolysed to ROH slowly but the reaction is rapid if a catalytic amount of KI is added to the reaction mixture.

• 5)

(R)-2- Bromooctane reacts with NaSH to form (S)-2- octanethiol with inversion of configuration at the stereocentre.How can we obtain (R)-2 octanethiol from (R)-2-bromoctane?

#### CBSE 12th Standard Chemistry - Coordination Compounds Five Mark Model Question Paper - by Sudha George - Kochi - View & Read

• 1)

Using crystal field theory, draw energy level diagram, write electronic configuration of the central metal atom/ion and determine the magnetic moment value in the following :

(i) $[CoF_6]^{3-}, [Co(H_2O)_6]^{2+},[Co(CN)_6]^{3-}$

(ii) $[FeF_6]^{3-}, \ [Fe(H_2O)_6]^{2+}, [Fe(CN)_6]^{4-}$.

• 2)

Using valence bond theory, explain the following in relation to the complexes given below :

$[Mn(CN)_6]^{3-}, [Co(NH_3)_6]^{3+}, [Cr(H_2O)_6]^{3+}, [FeCl_6]^{4-}$

(i) Type of hybridisation     (ii) Inner or outer orbital complex.     (iii) Magnetic behaviour.     (iv) Spin only magnetic moment value.

• 3)

CoSO4Cl.5 NHexists in two isomeric forms 'A' and 'B' gives white precipitate with BaClbut does not react with AgNO3.  Answer the following questions.

(i) Identify 'A' and 'B' and write their structure formulas.     (ii) Name the type of isomerism involved     (iii) Give the IUPAC name of 'A' and 'B'.

• 4)

What is the relationship between observed colour of the complex and the wavelength of light absorbed by the complex ?

• 5)

Why are different colours observed in octahedral and tetrahedral complexes for the same metal and same ligands ?

#### CBSE 12th Standard Chemistry - The d- and f- Block Elements Five Mark Model Question Paper - by Sudha George - Kochi - View & Read

• 1)

(a) Given below the following characteristics of the first series of the transition metals and their trends in the series (Sc to Zn):

(ii) Oxidation status

(iii) Ionisation enthalpies

(b) Name an important alloy which contains some of the lanthanoid metals. Mention its two uses.

• 2)

Calculate the number of unpaired electrons in following gaseous ions: Mn3+, Cr3+, V3+ and Ti3+. Which one of these is the most stable in aqueous solution?

• 3)

Compare the general characteristics of the first series of the transition metals with those of the second and third columns. Give special emphasis on the following points:

(i) electronic configurations,

(ii) oxidation states,

(iii) ionisation enthalpies and

(iv) atomic sizes.

• 4)

(a) Out of Ag2SO4, CuF2, MgF2 and CuCI, which compound will be coloured and why ?

(b) Explain : (i) ${ CrO }_{ 4 }^{ 2- }$ is a strong oxidizing agent while ${ MnO }_{ 4 }^{ 2- }$ is not. (ii) Zr and Hf have identical sizes.

(iii) The lowest oxidation state of manganese is basic while the highest is acidic.

(iv) Mn (II) shows maximum paramagnetic character amongst the divalent ions of the first transition series.

• 5)

Complete the following chemical reaction equations:

(i) $CrO_{ 7 }^{ 2\quad - }(aq)+H_{ 2 }S(g)+H^{ + }(aq)\longrightarrow$

(ii) $CrO_{ 7 }^{ 2\quad - }(aq)+H_{ 2 }S(g)+H^{ + }(aq)\longrightarrow$

(b) Explain the following observations:

(i) Transition metals form compounds which are usually coloured.

(ii) Transition metals exhibit variable oxidation states.

(iii) The actinoids exhibit a greater range of oxidation states than the lanthanoids.

#### 12th Standard CBSE Chemistry - The p-Block Elements Five Mark Question Paper - by Sudha George - Kochi - View & Read

• 1)

(a) Complete the following chemical equations:

(i) Cu + HNO3(dilute) $\to$

(ii) XeF4 + O2F2 $\to$

(b) Explain the following observations:

(i) Phosphorus has greater tendency for catenation than nitrogen.

(ii) Oxygen is a gas but sulphur a solid.

(iii) The halogens are coloured.  Why?

• 2)

(a) Draw the structures of the following molecules:

(i) (HPO3)3

(ii) BrF3

(b) Complete the following chemical equations:

(i) HgCl2 + PH3 $\to$

(ii) SO3 + H2SO$\to$

(iii) XeF4 + H2$\to$

• 3)

(a) Draw the structures of the following:

(i) N2O5

(ii) XeOF4

(b) Explain the following observations:

(i) The electron gain enthalpy of sulphur atom has a greater negative value than that of oxygen atom.

(ii) Nitrogen does not form pentahalides.

(iii) In aqueous solutions, HI is a stronger acid than HCl.

• 4)

(a) Draw the structures of the following:

(i) XeF4     (ii) H2S2O7

(b) Explain the following observations:

(i) Phosphorus has a greater tendency for catenation than nitrogen.

(ii) The negative value of electron gain enthalpy is less for fluorine than that for chlorine.

(iii) Hydrogen fluoride has a much higher boiling point than hydrogen chloride.

• 5)

(a) Complete the following chemical equations:

(i) F2 + H2        $\to$ .............

(ii) Ca3P2 + H2O   $\to$ .............

(iii) XeF4 + H2O    $\to$ .............

(b) Draw structures of the following species:

(i) H2S2O7 (ii) NO3-

#### 12th Standard CBSE Chemistry - Electrochemistry Five Marks Questions - by Archana Singh - Deoghar - View & Read

• 1)

On the basis of the following data, explain why Co(III) is not stable in aqueous solution ?

${ Co }^{ 3+ }+{ e }^{ - }\longrightarrow { Co }^{ 2+ },{ E }^{ 0 }=+1.82V$

$2{ H }_{ 2 }O\longrightarrow { O }_{ 2 }+4{ H }^{ + }+{ 4e }^{ - },{ E }^{ 0 }=1.23V$

• 2)

A voltaic cell is set up at $25°$C with the half cells Ag+(0.001 M)Ag and Cu2+(0.10M)Cu. What should be its cell potential?

• 3)

India is a very big country and is in a phase of modernisation. There is an enormous shortage of electricity and as a result, our industrial growth is hampered. There are major cuts both at household and domestic levels. These days, there is a major emphasis on the use of solar energy.
(i) How is the solar power used in a country like India?
(ii) As a student, how will you promote the use of solar power?

• 4)

Calculate the $\triangle G^{ 0 }$   and emf (E) that can be obtained from the following cell under the standard conditions at 25°C.
Zn(s) IZn2+(aq) IISn2+(aq) I Sn(s)
[Given $E^{ 0 }_{ Zn2+/Zn }=-0.76V;$ $E^{ 0 }_{ sin2+/sn }=-0.14V$ ]
and F= 96500 C mol-1

• 5)

(i) The conductivity of 0.001 mol L-1 solution of CH3COOH is 3.905x10-5 S cm-1. Calculate its molar;. conductivity and degree of dissociation. Given
$\lambda ^{ 0 }\left( H^{ + } \right) =349.6Scm^{ 2 }mol^{ -1 }$ and
$\lambda ^{ 0 }\left( CH_{ 3 }COO^{ - } \right) =40.9\quad scm^{ 2 }mol^{ -1 }$
(ii) Define electrochemical cell. What happens if external potential applied becomes greater than E0cell of electrochemical cell?

#### 12th Standard CBSE Chemistry - Solution Five Marks Questions - by Archana Singh - Deoghar - View & Read

• 1)

(a) State the following:
(i) Henry's law about partial pressure of gas in a mixture.
(ii) Raoult's law in its general form in reference to solutions.
(b) A solution prepared by dissolving 8.95 mg of a gene fragment in 35.0 ML of water has an osmotic pressure of 0.335 torr at 25oC. Assuming gene fragment is non-electrolyte, determine its molar mass.

• 2)

(a) Assuming complete ionization, calculate the expected freezing point of solution prepared by dissolving 6.00 g of Glauber's salt, Na2SO4. 10H2O in 0.1 kg of H2O. (K f for H2O = 1.86 K kg mol-1) [At. mass of Na = 23, S = 32, O= 16, H = 1 u].
(b) Two liquids X and Y boil at 110 oC and 130 oC respectively. Which of them has higher vapor pressure at 50oC ?

• 3)

(a) Define Azeotropes and explain broefly minimum boiling azeotrope by taking suitable example.
(b) The vapour pressures of pure liquids A and B are 450 mm 700 mm of Hg respectively at 350 K. Calculate the composition of the liquid mixture if total vapour pressure is 600 mm of Hg. Also find the composition of the mixture in the vapour phase.

• 4)

The elements A and B form purely covalent compounds having molecular formulae AB2 and AB4. When dissolved in 20g of benzene, 1g of AB2 lowers the freezing point by 2.3K, whereas 1g of AB4 lowers it by 1.3K. the molal depression constant for benzene is 5.1 K kg/mol, calculate the atomic mass of A and atomic mass of B. (A=25.59, B=42.64).

• 5)

a) Why constant boiling mixtures behave like a single component when subjected to distillation.
b) What type of Azeotropic mixtures are formed by the following solution
i) H2O and HCl ii) H2O and C2H5OH
c) Give one practical application of depression of freezing point?
d) A Solid solution is formed between two substances. One whose particles are very large and the other particles are very small. What type of solid solution is this likely to be?
e) Write the Raoults Law for each component of a binary solution and show that the total vapour pressure of the solution may be expressed as P = P0A + (P0B – P0A) XB.

#### 12th Standard CBSE Chemistry - The Solid State Five Marks Questions - by Archana Singh - Deoghar - View & Read

• 1)

What is meant by anisotropy? Which of the two : quartz or glass shows this property?

• 2)

Define the following terms:
(i) ferromagnetism
(ii) Ferrimagnetism

• 3)

Define the following:
(i) Dislocation
(ii) F-centre
(iii) Anti-ferroelectric

• 4)

What type of structure is generally adopted by alkali metal halides at ordinary temperature and pressure? What happens to structure when pressure is applied to alkali metal halides?

• 5)

What are point defects in crystals and how do they develop?

#### CBSE Class 12th Chemistry - The p-Block Elements Three Marks Questions - by Archana Singh - Deoghar - View & Read

• 1)

Account for the following:

(i) BiCl3 is less covalent than PCl3

(ii) O3 acts as a powerful oxidising agent.

(iii) F2 is a stronger oxidising agent than Cl2

• 2)

Give reasons for each of the following:

(a) Sulphur in vapour state exhibits paramagnetic behaviour.

(b) Hydrogen fluoride is weaker acid than hydrogen chloride in water.

(c) NH3 has higher proton affinity than PH3.

• 3)

Describe the following about halogen family (group 17 elements):

(i) Relative oxidising power

(ii) Relative strength of their hydrides

(iii) Oxyacids and their related oxidising ability.

• 4)

An organic compound A gives a brick red flame on performing flame test. The compound gives the following tests also
I. It gives smell of chlorine when placed in moist air.
II. If KI and CH3COOH are added to the solution of the compound a violet colour is observed.
Identify the compound and write the chemical reactions for the steps (I) and (II).

• 5)

Give reasons for each of the following observations
I. Only higher members of the group 18 of the periodic table are expected to form compounds.
II. NO2 readily forms a dimer whereas ClO2 doesn’t.

#### CBSE Class 12th Chemistry - The d- and f- Block Elements Three Marks Questions - by Archana Singh - Deoghar - View & Read

• 1)

How would you account for the following ?

(i) The atomic radii of the metals of the third (5d) series of transition elements are virtually the same as those of the corresponding members of the second (4d) series.

(ii) The Eo value for the Mn3+/Mn2+ couple is much more positive than that for Cr3+/Cr2+ couple or Fe3+/Fe2+ couple.

(iii) The highest oxidation state of a metal is exhibited in its oxide or fluoride.

• 2)

Explain the following:

(i) The transition elements have great tendency for complex formation.

(ii) There is a gradual decrease in the atomic sizes of transition elements in a series with increasing atomic numbers.

(iii) Lanthanum and Lutetium do not show colouration in solutions.

(At. No.: La=57, Lu=71)

• 3)

Give reasons for each of the following:

(i) Size of trivalent lanthanoid cations decreases with increase in the atomic number.

(ii) Transition metal fluorides are ionic in nature, whereas bromides and chlorides are usually covalent in nature.

(iii) Chemistry of all the lanthanoids is quite similar.

• 4)

Identify the first row transition metal ions which have outer electronic configurations of 3d4 and 3d6 and describe their oxidation states.

• 5)

Complete the following reactions:

(a) Cr2O72-+14H++6e-$\longrightarrow$.......... +7H2O

(b) CrO42-+..........$\rightleftharpoons$........$\rightleftharpoons$.......+H2O

(c) MnO4-+2H2O+3e$\overrightarrow { medium }$........ +4OH-

#### CBSE Class 12th Chemistry - Coordination Compounds Three Marks Questions - by Archana Singh - Deoghar - View & Read

• 1)

Write the name, the state of hybridization, the shape and the magnetic behaviour of the following complexes:

[Ni(CN)4]2-, [CoCl4]2-,[Cr(H2O)2(C2O4)2]-

(At. No.:Co=27, Ni=28, Cr=24)

• 2)

Give the formula of each of the following coordination entities:
(i) Co3+ ion is bound to one Cl-, one NH3 molecule (en) molecules.
(ii) Ni2+ ion is bound to two water molecules and two oxalate ions.

• 3)

Write the name, stereochemistry and magnetic behaviour of the following:

(At. nos. Mn=25, Co=27, Ni=28)

(i) K4(Mn(CN)6]

(ii) [Co(NH3)5Cl]Cl2

(iii) K2[Ni(CN)4]

• 4)

(a) Square planar complexes (of MX2Ltype) with coordination number of 4 exhibits geometrical isomerism whereas tetrahedral complexes with similar composition do not. Why?
(b) Describe the type of hybridization, shape and magnetic property of [Co(NH3)4Cl2]Cl.
[Give: At. no.of Co=27]

• 5)

Compare the following complexes with respect to structural shapes of units, magnetic behaviour and hybrid orbitals involved in units:

(i) [Ni(CN)4]2-

(ii) [NiCl4]2-

(iii) [CoF6]3-

[At. nos: Ni=28: Co=27]

#### CBSE Class 12th Chemistry - Haloalkanes and Haloarenes Three Marks Questions - by Archana Singh - Deoghar - View & Read

• 1)

Complete the following reactions:

(i) $CH_3CH_2OH \xrightarrow{SOCI_2}'A' \xrightarrow{KCN} 'B'$

(ii) $CH_3-CH-CH_3 \xrightarrow{PCl_5} 'A' \xrightarrow{AgCN}'B' \\ \quad \quad \quad \ \ | \\ \quad \quad \quad \ OH$

(iii) $CH_3CH_2\xrightarrow{AgNO_2}\ 'A'$

(iv) (CH3)2CHCI + CH $\equiv$ CNa $\rightarrow$ 'A'

(v) $CH_3CH_2CH_2Cl+CH_3​​​​​​​COOAg \rightarrow \ 'A' +\ 'B'$

(vi) $2(CH_2)_2CHBr + 2Na \xrightarrow{dry \ ether}$

• 2)

An organic compound 'A' having molecular formula C4H8 on treatment with dil.  H2SO4 gives 'B'.  'B' on treatment with conc.  HCl and anhydrous ZnCl2 gives 'C' and on treatment with sodium ethoxide gives back 'A'.  Identify the compounds 'A', 'B' and 'C' and write the equations involved.

• 3)

An alkyl chloride (A), on reaction with magnesium in dry ether followed by treatment with ethanol gave 2-methylbutane.  Write all the possible structures of (A).

• 4)

Explain why
(a) vinyl chloride is unreactive in nucleophilic substitution reactions?
(b) neo-pentyl bromide undergoes nucleophilic substitution reaction very slowly?
(c) 3-bromocyclohexene is more reactive than 4-bromocyclohexene in hydrolysis with aqueous NaOH?
(d) tert-butyl chloride reacts with aqueous sodium hydroxide by SN1 mechanism while n-butyl chloride reacts by SN2 mechanism?

• 5)

Arrange the compounds of each set in order of reactivity towards SN2 displacement:
(a) 2-Bromo-2-methylbutane, 1-Bromopentane, 2-Bromopentane
(b) 1-Bromo-3-methylbutane, 2-Bromo-2-methylbutane, 3-Bromo-2-methylbutane
(c) 1-Bromobutane, 1-Bromo-2,2-dimethylpropane, 1-Bromo-2-methylbutane, 1-Bromo-3-methylbutane

#### CBSE Class 12th Chemistry - Alcohols , Phenols and Ethers Three Marks Questions - by Archana Singh - Deoghar - View & Read

• 1)

Draw the structure and name the product formed if the following alcohols are oxidized. Assume that an excess of oxidizing agent is used.
(i) CH3CH2CH2CH2OH
(ii) 2-butenol
​​​​​​​(iii) 2-methyl-1-propanol

• 2)

An organic compound (A) having molecular formula C6H6O gives a charactertic colour with aqueous FeCl3 solution (A) on treatment with CO2 and NaOH at 400 K under high pressure gives (B) which on acidification gives a compound (). C reacts with acetyl choride to give (D), which is a popular Pain Killer. Deduce the structures of (A), (B), (C) and (D).

• 3)

Wrire the chemical equation and reaction conditions for the concersion of
II. Methanol to ethanol
III. Anisole to 4-methoxyacephenone

• 4)

Name the reagents for the following
I. Oxidation of primary alcohol to aldehyde
II. Oxidation of primary alcohol to carboxylic acid
III. Dehydration of prapan-2-ol to propene.
IV. Reduction of butan-2-one to butan-2 ol.

• 5)

Complete the following reaction.

#### CBSE Class 12th Chemistry - Aldehydes , Ketones and Carboxylic Acids Three Marks Questions - by Archana Singh - Deoghar - View & Read

• 1)

(a) Write the step and conditions involved in the following conversions:
(i) Acetophenone to 2-phenyl-2-butanol
(ii) Propene to acetone
(b) Describe simple chemical tests to distinguish between the following pairs of compounds:
Diethyl ether and Propanol

• 2)

How will you carry out the following conversions:
(i) Acetone to chloroform?
(ii) Acetylene to Acetic acid?

• 3)

Why is carboxyl group in benzoic acid meta directing?  Support your answer with two examples.

• 4)

An aliphatic compound 'A' with a molecular formula of C3H6O reacts with phenylhydrazine to give compound 'B'.  Reaction of 'A' with I2 in alkaline medium on warming, gives a yellow precipitate 'C'.  Identify the compounds A, B and C.

• 5)

Write chemical reactions to affect the following transformations:
(a) Butan-1-ol to butanoic acid
(b) Benzyl alcohol to phenylethanoic acid
(c) 3-Nitrobromobenzene to 3-nitrobenzoic acid
(d) 4-Methylacetophenone to benzene-1, 4-di-carboxylic acid
(e) Cyclohexene to hexane-1,6-dioic acid
(f) Butanal to butanoic acid.

#### CBSE Class 12th Chemistry - Organic Compounds Containing Nitrogen Three Marks Questions - by Archana Singh - Deoghar - View & Read

• 1)

An aliphatic compound 'A' with molecular formula C2H3Cl on treatment with AgCN hives two isomeric compounds of unequal amounts with the molecular formula C3H3N. The minor of nthese two products on complete reduction with Hin the presence of Ni gives a compound 'B' with  molecular formula C3H9N. Identify the compounds 'A' , 'B' and write the reactions involved.

• 2)

Iodomethane reacts with KCN to form a major product 'A' . Compund 'A' on reduction in presence of LiAIH4 forms a higher amine 'B'. Compound B on treatment with CuCl2 frms a blue colour complex 'C'. Identify the compounds 'A', 'B'  and 'C' .

• 3)

An organic compound 'A' having molecular formula C2H5O2N reacts with HNO2 and gives'B' C2H4O3N2. On reduction, 'A' gives a compound 'C' on treatment with HNO gives 'D' which gives positive iodoform test. Identify 'A' .

• 4)

How will you convert:
(i) Benzene into aniline?
(ii) Benzene into N, N-dimethylaniline?
(iii) Cl-(CH2)4-Cl into hexan-1,6-diamine?

• 5)

Convert:
(i) 3-Methylaniline into 3-nitrotoluene,
(ii) Aniline into 1,3,5-tribromobenzene.

#### CBSE Class 12th Chemistry - Biomolecules Three Marks Questions - by Archana Singh - Deoghar - View & Read

• 1)

How can reducing and non-reducing sugars be distinguished? Mention the structural feature characterizing reducing sugars

• 2)

Explain the following terms

(i)Mutarotation

(ii)Avitaminosis

• 3)

(i)What are reducing sugars?
(ii) What is meant by denaturation of a protein?
(iii)How is oxygen replenished in our atmosphere?

• 4)

Name the main diseases caused due to lack of vitamin and its source in each of the following: A,B6 and E6 and E.

• 5)

Define the following terms:

(i)Co-enzymes

(ii)Mutation in biomolecules

(iii)Nucleotides

#### CBSE Class 12th Chemistry - Polymers Three Marks Questions - by Archana Singh - Deoghar - View & Read

• 1)

Explain the following terms giving a suitable example for each :

(i) Elastomers

(ii) Condensation polymers

• 2)

Write chemical equations for the synthesis of

(a) terylene

(b) neoprene

(c) teflon

• 3)

Giving one example each of

(ii) condensation polymers,

(iii) copolymers.

• 4)

Write the mechanism of free radical polymerization of ethene.

• 5)

Which of the following polymers soften on heating and harden on cooling? What are the polymers with this property collectively called? What are the structural similarities between such polymers Bakelite, urea-formaldehyde resin, polythene, polyvinyl, polystyrene.

#### CBSE Class 12th Chemistry - Chemistry in Everyday Life Three Marks Questions - by Archana Singh - Deoghar - View & Read

• 1)

(a) Differentiate between disinfectant and an antiseptic. Give one example of each.
(b) What is tincture of iodine and what is it used for?

• 2)

• 3)

Mention the action of the following on the human body in bringing relief from a disease.
(i) Brompheniramine
(ii) Aspirin
(iii) Equalin

• 4)

Explain the following types of substances with one suitable example, for each case:
(i) Cationic detergents
(ii) Food preservatives.
(iii) Analgesics.

• 5)

What are detergents? How are they classified? Why are detergents usually preferred to soaps for washing clothes? Give an example of detergents.

#### CBSE Class 12 Chemistry - General Principles and Processes of Isolation of Elements Three Marks Questions - by Archana Singh - Deoghar - View & Read

• 1)

How can  you obtain pure alumina form a bauxite ore associated with silica? Write the reactions involved in this process.

• 2)

Write the reactions involved in the following processes:

(i) Leaching of bauxite ore to prepare pure alumina.

(ii) Refining of zirconium by van Arkel method.

(iii) Recovery of gold after gold ore has been leached with NaCN solution.

• 3)

State the role of

(i) depressant in froth floatation process.

(ii) silica in the metallurgy of copper.

(iii) graphite rod in the electrolytic reduction of alumina.

• 4)

Describe the role of the following:

(i) NaCN in the extraction of silver from a silver ore.

(ii) Iodine in the refining of titanium

(iii) Cryolite in the metallurgy of aluminium

• 5)

Write down the reactions taking place in different zones in the blast furnace during the extraction of iron.

#### CBSE 12th Standard Chemistry - General Principles and Processes of Isolation of Elements Five Mark Question Paper - by Sudha George - Kochi - View & Read

• 1)

State the role of

(i) depressant in froth floatation process.

(ii) silica in the metallurgy of copper.

(iii) graphite rod in the electrolytic reduction of alumina.

• 2)

Explain:

(i) Zone refining

(ii) Column chromatography.

• 3)

The reaction:

${ Cr }_{ 2 }{ O }_{ 3 }+2Al\rightarrow { Al }_{ 2 }{ O }_{ 3 }+2Cr;\quad \triangle { G }^{ ° }=-421\quad kJ$ is thermodynamically feasible as is apparent from Gibbs energy value. Why does it not take place at room temperature?

• 4)

Explain the role of

(i) cryolite in the electrolytic reduction of alumina.

(ii) carbon monoxide in the purification of nickel.

• 5)

(i) Name the method of refining of metals such as germanium.

(ii) In the extraction of Al, impure ${ Al }_{ 2 }{ O }_{ 3 }$ is dissolved in conc. NaOH to form sodium aluminate and leaving impurities behind. What is the name of this process?

(iii) What is the role of coke in the extraction of iron from its oxides?

#### 12th Standard CBSE Chemistry - Surface Chemistry Five Mark Question Paper - by Sudha George - Kochi - View & Read

• 1)

Explain the following:
(a) Same substance can act both as colloids and crystalloids.
(b) Artifical rain is caused by spraying salt over clouds.
(c) When a beam of light is passed through a colloidal sol, the path of the beam gets illuminated.

• 2)

What is demulsification? Name two demulsifiers.

• 3)

Explain the following terms:
(i) Electrophoresis
(ii)Coagulation
(iii) Dialysis
(v) Tyndal effect

• 4)

Write one difference in each of the following:
(i) Lyophobic sol and lyophilic sol.
(ii) Solution and colloid.
(iii) Homogeneous catalysis and heterogeneous catalysis

• 5)

(i) In reference to Freundlich's adsorption isotherm, write the expression for adsorption of gases on solids in the form of an equation.
(ii) Write an important characteristic of lyophilic sols.
(iii) Based on the type of particles of dispersed phase, give one example each of associated colloid and multimolecular colloid.

#### 12th Standard CBSE Chemistry - Chemical Kinetics Five Mark Question Paper - by Sudha George - Kochi - View & Read

• 1)

(a) what is meant by rate of a reaction.

(b) In a pseudo first order hydrolysis of ester in water, the following results are obtained:

 t in seconds 0 30 60 90 [Ester] M 0.55 0.31 0.17 0.085

(i) Calculate the average rate of reaction between the time interval 30 to 60 seconds.

(ii) Calculate the pseudo first order rate constant for the hydrolysis of ester.

• 2)

(a) Define the following:

(i) Order of a reaction

(ii) Elementary step in a reaction

(b) A first order reaction has a rate constant value of 0.00510 min-1.  If we begin with 0.10 M concentration of the reactant, how much of the reactant will remain after 3.0 hours?

• 3)

(a) Explain the following terms:
(i) Order of a reaction
(ii) Molecularity of a reaction
(b) The rate of a reaction increases four times when the temperature changes from 300 k to  320 K.  Calculate the energy of activation of the reaction, assuming that it does not change with temperature.
(R = 8.314 J K-1 mol-1)

• 4)

(a) List the factors that control the rate of a chemical reaction.

(b) The half-life for decay of radioactive 14C is 5730 years.  An archaeological artefact containing wood had only 80% of 14 C activity as found in a living tree.  Calculate the age of the artefact

• 5)

Describe briefly the dependence of reaction rate of a chemical reaction on temperature. Explain the effect of temperature on the rate constant of a reaction.

#### 12th CBSE Chemistry - Electrochemistry Five Mark Question Paper - by Sudha George - Kochi - View & Read

• 1)

(a) Define molar conductivity of a solution and explain how molar conductivity changes with change in concentration of solution for a weak and a strong electrolyte.
(b) The resistance of a conductivity cell containing 0.001 M KCl solution at 298 K is 1500 $\Omega$. What is the cell constant if the conductivity of 0.001 M KCl solution at 298 K is $0.146\times { 10 }^{ -3 }S{ cm }^{ -1 }$?

• 2)

Three electrolytic cells A,B,C containing solutions of ZnSO4,AgNO3 and CuSO4, respectively are connected in series. A steady current of 1.5 amperes was passed through them until 1.45 g of silver deposited at the cathode of cell B. How long did the current flow? What mass of copper and zinc were deposited?

• 3)

Tarnished silver contains Ag2 S. Can this tarnish be removed by placing tarnished silver ware in an aluminium pan containing an inert electrolytic solution such as NaCl ? The standard electrode potential for the half reactions are : For ${ Ag }_{ 2 }S(s)+{ 2e }^{ - }\longrightarrow 2Ag(s)+{ S }^{ 2- },$ it is - 0.71 V and for ${ Al }^{ 3+ }+{ 3e }^{ - }\longrightarrow Al(s)$, it is - 1.66 V

• 4)

Three iron sheets have been coated separately with three metals (A, B and C) whose standard electrode potentials are given below :

 Metal A B C Iron E0value - 0.46 - 0.66 V - 0.20 V - 0.44 V

Identify in which case rusting will take place faster when coating is damaged.

• 5)

A voltaic cell is set up at $25°$C with the half cells Ag+(0.001 M)Ag and Cu2+(0.10M)Cu. What should be its cell potential?

#### 12th Standard CBSE Chemistry - Solution Five Mark Question Paper - by Sudha George - Kochi - View & Read

• 1)

Alternative definition of Henry's law

• 2)

Konowaloff's rule.

• 3)

How many grams of sucrose (M.wt. = 342) should be dissolved in 100g water in order to produce a solution with 105.0°C difference between the freezing point and the boiling point ?(Kf = 1.86°C/m, Kb = 0.51°C/m)

• 4)

(a)  Differentiate between molarity and molality for a solution. How does a change in temperature influence their values?
(b) Calculate the freezing point of an aqueous solution containing 10.50 g of MgBr2 = 184 g) (K f for water 1.86 K kg mol-1)

#### 12th CBSE Chemistry - The Solid State Five Mark Question Paper - by Sudha George - Kochi - View & Read

• 1)

Predict the structure of MgO crystal and coordination number of its cation in which cation and anion radii are equal to 65 pm and 140 pm respectively.

• 2)

Calculate the approximate numbert of unit cells present in 1 g of ideal NaCl crystals.

• 3)

What are ferromagnets and ferro-electrics? Give on example of each case.

• 4)

What are point defects in crystals and how do they develop?

#### CBSE 12th Chemistry - Surface Chemistry Three Marks Questions - by Archana Singh - Deoghar - View & Read

• 1)

• 2)

(a) How can a colloidal solution and true solution of the same colour be distinguished from each other?

(b) List four applications of adsorption.

• 3)

(a) Which will be adsorbed more readily on the surface of charcoal and why? NH3 or CO2
(b) In what way are multimolecular colloids different from macromolecular colloids? Give one example of each,
(c) State the principle of electrodialysis.

• 4)

(a) In which of the following does adsorption take place and why?
(i) Silica gel placed in the atmosphere saturated with water.
(ii) Anhydrous CaCl2 placed in the atmosphere saturated with water.
(b) How does BF3 act as a catalyst in industrial process?
(c) Give an example of shape-selective catalysis.

• 5)

Define the following:
(i) Cationic detergents
(iii) Tranquilisers

#### CBSE 12th Chemistry - Chemical Kinetics Three Marks Questions - by Archana Singh - Deoghar - View & Read

• 1)

A first order reaction takes 100 minutes for completion of 60% of the reaction.  Find the time when 90% of the reaction will be completed.

• 2)

In general it is observed that the rate of chemical reaction doubles with every 10o rise in temperature.  If the generalization holds good for the reaction in the temperature range 295 K to 305 K, what would be the value of activation energy for the this reaction?
(R = 8.314 J mol-1  K-1)

• 3)

The reaction,
N2(g) + O2(g) $\rightleftharpoons$2NO(g)
Contributes to air pollution whenever a fuel is burnt in air at a high temperature.  At 1500 K, equilibrium constant K for it is 1.0 $\times$ 10-5.  Suppose in a case [N2] = 0.80 mol L-1and [O2] = 0.20 mol L-1 before any reaction occurs. Calculate the equilibrium concentration of the reactants and the product after the mixture has been heated to 1500 K.

• 4)

The half-life for the decomposition of nitramide is 2.1 hour at 15 oC

NH2NO2(aq) $\to$ N2O (g) + H2O(l)

If 6.2 g of NH2NO2 is allowed to decompose, calcualte

(i) time taken for NH2NO2 to decompose 99%

(ii) volume of N2O (dry) produced at STP.

• 5)

The half-life for the reaction:

N2OS $\to$ 2NO2 + $1\over2$O2 is 2.4 hours at 30 oC.

(a) Starting with 100 grams of N2Os, how many gram will remain after 9.6 hours?

(b) What time would be required to reduce 5 $\times$ 1010 molecules of N2O5 to 108 molecules?

#### 12th Standard CBSE Chemistry - Electrochemistry Three Marks Questions - by Archana Singh - Deoghar - View & Read

• 1)

An aqueous solution of copper sulphate, CuSO4 was electrolysed between platinum electrodes using a current of  0.1287 ampere for 50 minutes. (Atomic mass of Cu=63.5 g mol-1].

(a) Write the cathodic reaction.

(b) Calculate:

(i) Electric charge passed during electrolysis.

(ii) Mass of copper deposited at the cathode

[Given : 1F = 96,500 C mol-1]

• 2)

For the cell

$Zn(s)\left| { Zn }^{ 2+ }(2M) \right| \left| { Cu }^{ 2+ }(0.5M) \right| Cu(s)$

(a) Write equation for each half-reaction.

(b) Calculate the cell potential at 25 oC.

[Given: ${ E }_{ { Zn }^{ 2+ }/Zn }^{ o }=-0.76V;{ E }_{ { Cu }^{ 2+ }/Cu }^{ o }=+0.34V$]

• 3)

The Eo values at 298 K corresponding to the following two reduction electrode processes are:

(i) Cu+/Cu=+0.52 V

(ii) Cu2+/Cu+=+0.16 V

Formulate the galvanic cell for their combination. What will be the cell potential? Calculate the ${ \triangle }_{ r }{ G }^{ o }$ for the cell reaction.(1F=96500 C mol-1).

• 4)

Calculate the standard cell potentials of galvanic cell in which the following reactions take place:

(i) $2Cr(s)+{ 3Cd }^{ 2+ }(aq)\rightarrow { 2Cr }^{ 3+ }(aq)+3Cd(s)$

(ii) ${ Fe }^{ 2+ }(aq)+{ Ag }^{ + }(aq)\rightarrow { Fe }^{ 3+ }(aq)+Ag(s)$

Calculate the ${ \triangle }_{ r }{ G }^{ o }$ and equilibrium constant for the reactions.

${ E }_{ { Cr }^{ 3+ }/Cr }^{ o }=-0.74V,\quad { E }_{ { Cd }^{ 2+ }/Cd }^{ o }=-0.40V,\quad { E }_{ { Fe }^{ 3+ }/{ Fe }^{ 2+ } }^{ o }=+0.77V,\quad { E }_{ { Ag }^{ + }/Ag }^{ o }=+0.80V$

• 5)

A solution of CuSO4 is electrolysed for 10 minutes with a current of 1-5 amperes. What is the mass of copper deposited at the cathode? (Molar mass of Cu = 63.5 g mol-1)

#### 12th CBSE Chemistry - Chemistry in Everyday Life Two Marks Questions - by Archana Singh - Deoghar - View & Read

• 1)

A solution of urea in water has a boiling point of 373.128 K. Calculate the freezing point of the same solution. [Given: For water, K f = 1.86 Km-1, Kb = 0.52 Km-1]

• 2)

0.1 mole of acetic acid was dissolved in 1 kg of benzene. Depression in freezing point of benzene was determined to be 0.256 K. what conclusion can you draw about the state of the solute in solution? [Given: Kf for benzene = 5.12 K/m]

• 3)

A 0.1539 molal aqueous solution of cane sugar (mol. mass = 342 g mol -1) has a freezing point of 271 K while the freezing point of pure water is 273.15 K. what will be the freezing point of an aqueous solution containing 5 g of glucose (mol. mass = 180 g mol-1) per 100 g of solution?

• 4)

The vapour pressure of water is 12.3 kPa at 300 K. Calculate vapour pressure of 1 molal solution of a non-volatile solute in it.

• 5)

What role does the molecular interaction play in solution of alcohol and water?

#### 12th Standard CBSE Chemistry Unit 1 The Solid State Three Marks Questions - by Archana Singh - Deoghar - View & Read

• 1)

Explain the following properties given suitable examples:

(i) Ferromagnetism;

(ii) Paramagnetism;

(iii) Ferrimagnetism.

• 2)

Silver crystallizes in face-centred cubic unit cell. Each side of this unit cell has a length of 400 pm. Calculate the radius of the silver atom. (Assume the atoms just touch each other on the diagonal across the face of the unit cell. That is , each face atom is touching the four corner atoms.)

• 3)

The well-known mineral fluorite is chemically calcium fluoride. It is known that in one unit cell of this mineral, there are 4 Ca2+ ions and 8 Fions and that Ca2+ ions are arranged in a fcc lattice. The F- ions fill all tetrahedral holes in the face-centred cubic lattice of Ca2+ ions. The edge of the unitcell is 5.46$\times$10-8 cm in length. The density of the solid is 3.18 g cm-3. Use this information to calculate Avogadro's number. (Molar mass of CaF2=78.08 G mol-1)

• 4)

Calculate the efficiency of packing in case of a metal crystal for
(a) simple cubic,
(b) body-centred cubic, and
(c) face-centred cubic (with the assumption that atoms are touching each other).

• 5)

What makes a glass different from a solid such as quartz? Under what conditions could quartz be converted into glass?

#### 12th Standard CBSE Chemistry - Chemistry in Everyday Life Two Marks Questions - by Archana Singh - Deoghar - View & Read

• 1)

Explain the cleaning action of soap. Why do soaps not work in hard water?

• 2)

What are food preservatives? Name two such substance.

• 3)

Name the medicines used for the treatment of the following diseases:

(i) Tuberculosis

(ii) Typhoid

• 4)

Why do we need to classify drugs in different ways?

• 5)

Explain the term target molecules or drug targets as used in medicinal chemistry.

#### 12th Standard CBSE Chemistry - Polymers Two Marks Questions - by Archana Singh - Deoghar - View & Read

• 1)

What is the role of benzoyl peroxide in addition polymerisation of alkenes ?

• 2)

Name the sub-groups into which polymers are classified on the basis of magnitude of intermolecular forces.

• 3)

How are polymers classified on the basis of structure ?

• 4)

Classify the following as addition and condensation polymers : Terylene, Bakelite, Polyvinyl chloride, polythene.

• 5)

What are polymers?Why are they called macromolecules?

#### CBSE 12th Chemistry - Biomolecules Two Marks Questions - by Archana Singh - Deoghar - View & Read

• 1)

How are carbohydrates classified?

• 2)

State two main differences between globular proteins and fibrous proteins.

• 3)

$\alpha -$ Helix is a secondary structure of proteins formed by twisting of polypeptide chain into right handed screw like structures. which type of interactions are responsible for making the $\alpha -$ helix structure stable ?

• 4)

Why does compound (A) given below not form an oxime ?

• 5)

Activation energy for the acid catalysed hydrolysis of surcose is 6.22 kJmol-1, while the activation energy is only 2.15 kL mol-1 when hydrolysis is catalysed by the enzyme sucrase. Explain

#### 12th Standard CBSE Chemistry - Organic Compounds Containing Nitrogen Two Marks Questions - by Archana Singh - Deoghar - View & Read

• 1)

Why does bromination of aniline, even under very mild conditions give 2, 4, 6- tribromoaniline instantaneously?

• 2)

How can you convert p-toluidine to 2-bromo-4-methylaniline?

• 3)

Write chemical reaction of aniline with benzoyl chloride and write name of the product obtained.

• 4)

Write structures of different isomers corresponding to the molecular formula, C3H9N. Write IUPAC names of the isomers which will liberate nitrogen gas on treatment with nitrous acid.

• 5)

Write the reactions of
(i) aromatic and
(ii) aliphatic primary amines with nitrous acid.

#### 12th Standard CBSE Chemistry Unit 12 Aldehydes , Ketones and Carboxylic Acids Two Marks Questions - by Archana Singh - Deoghar - View & Read

• 1)

Give chemical tests to distinguish between the following pairs of compounds:
(i) Propanoyl chloride and Propanoic acid
(ii) Benzaldehyde and Acetophenone

• 2)

Draw the structures of the following compounds.
(i) 3-Methylbutanal
(ii) p-Methylbenzaldehyde
(iii) 4-Chloropentan-2-one
(iv) p, p'-Dihydroxybenzophenone

• 3)

Draw the structures of the following compounds.
(i) p-Nitropropiophenone
(ii) 4-Methylpent-3-en-2-one
(iii) 3-Bromo-4-phenylpentanoic acid
(iv) Hex-2-en-4-ynoic acid

• 4)

A compound 'A' with molecular formula C5H10O gave positive 2, 4-DNP test but a negative Tollen's reagent test.  It was oxdised to carboxylic acid 'B' with molecular formula C3H6O2 when treated with alkaline KMnO4 under vigorous condition.  Sodium salt of 'B' gave a hydrocarbon 'C' on Kolbe's electrolytic reduction.  Identify A, B and C and write the chemical equations for the reaction.

• 5)

Show how each of following compounds could be converted to benzoic acid.
(a) Ethylbenzene
(b) Acetophenone
(c) Bromobenzene
(d) Phenylethene (Styrene)

#### 12th Standard CBSE Chemistry - Alcohols , Phenols and Ethers Two Marks Questions - by Archana Singh - Deoghar - View & Read

• 1)

Write the reactions and the conditions involved in the conversion of :

(a) Propane to 1-Propanol

(b) Phenol to Salicylic acid

• 2)

How are the following conversions carried out? (Write the reactions and conditions in each case):

(i) Ethanol to 2-propanol

(ii) Phenol to Acetophenone

• 3)

Give the structures and IUPAC names of monohydric phenols of molecular formula, C7H8O.

• 4)

Give the equations of reaction for the preparation of phenol from cumene.

• 5)

How is 1-propoxypropane synthesized from propan-1-ol? Write mechanism of this reaction.

#### 12th Standard CBSE Chemistry - Haloalkanes and Haloarenes Two Marks Questions - by Archana Singh - Deoghar - View & Read

• 1)

What are ambident nucleophiles?  Explain with an example.

• 2)

Suggest a possible mechanism for the following reaction:

$n-BuBr + KCN \xrightarrow{EtOH_2,\ H_2O} n-BuCN$

• 3)

Identify the compounds A, B, C and D in the following sequence of reaction:

• 4)

Write the structural formulae of the organic compounds 'A', 'B', 'C' and 'D' in the following sequence of reaction:

• 5)

Why are haloarenes more stable than haloalkanes and undergo electrophilic substitution reaction at ortho and para positions?

#### CBSE 12th Chemistry - Coordination Compounds Two Marks Questions - by Archana Singh - Deoghar - View & Read

• 1)

Out of the following two coordination entities which is chiral (optically active)?

(a) cis-[CrCl2(ox)2]3-

(b) trans-[CrCl2(ox)2]3-

• 2)

The spin only magnetic moment of [MnBr4]2- is 5.9 B.M. Predict the geometry of the complex ion.

• 3)

Using IUPAC norms write the formula for the following:

(a) Pentaamminenitrito-O-cobalt (III)

(b) Pentaamminenitrito-N-cobalt (III)

• 4)

Using valence bond theory, explain the bonding in [Cr(H2O)6]3+. (At. No.of Cr=24).

• 5)

Write the IUPAC name of the complex [Cr(NH3)4Cl2]+. What type of isomerism does it exhibit?

#### 12th Standard CBSE Chemistry - The d- and f- Block Elements Two Marks Questions - by Archana Singh - Deoghar - View & Read

• 1)

Which metal in the first series of transition metals exhibits +1 oxidation state most frequently and why?

• 2)

The Eo(M2+/M) value for copper is positive (+0.34 V). What is possibly the reason for this? (Hint: consider its high ${ \Delta }_{ a }{ H }^{ o }$ and low ${ \Delta }_{ hyd }{ H }^{ o }$)

• 3)

Write chemical equations for the reactions involved in the manufacture of potassium permanganate from pyrolusite ore.

• 4)

What is meant by 'lanthanoids contraction'? State one use each of lanthanoid metals and their oxides.

• 5)

Describe the steps involved in the preparation of either potassium dichromate from sodium chromate or potassium permanganate from manganese dioxide.

#### 12th Standard CBSE Chemistry - The p-Block Elements Two Marks Questions - by Archana Singh - Deoghar - View & Read

• 1)

Describe the manufacture of H2SO4 by contact process.

• 2)

Write the conditions to maximise the yield of sulphuric acid by Contact process.

• 3)

Complete the following chemical reaction equations:

(i) I2 + HNO3 (conc.) $\to$

(ii) HgCl2 PH3 $\to$

• 4)

How would you account for the following?

(i) Hydrogen fluoride is much less volatile than hydrogen chloride.

(ii) Interhalogen compounds are strong oxidising agents>

• 5)

Assign a reason for each of the following:

(i) In group 15 the bond angle H-M-H decreases in the following order NH3 (107.8o), PH3 (93.6o), AsH3 (91.8o).

(ii) Sulphur hexafluoride is used as a gaseous electrical insulator.

#### CBSE 12th Chemistry Uint 6 General Principles and Processes of Isolation of Elements Two Marks Questions - by Archana Singh - Deoghar - View & Read

• 1)

Which of the ores of aluminium, iron, copper and zinc could be concentrated by magnetic method?

• 2)

Is it true under certain conditions Mg can reduce SiOand Si can reduce MgO? What are those conditions?

• 3)

Suggested a condition under which magnesium could reduce alumina

• 4)

Although thermodynamically feasible,in practice,magnesium metal is not used for the reduction of alumina in the metallurgy of aluminium.Why?

• 5)

Why is zinc not extracted from zinc oxide through reduction using CO?

#### 12th CBSE Chemistry Surface Chemistry Book Back Questions - by Archana Singh - Deoghar - View & Read

• 1)

(a) What happens when a freshly precipitated Fe(OH)3 is shaken with water containing a small quantity of FeCl3?

(b) Why is finely divided substance more effective as an adsorbent?

• 2)

What is the sign of $\Delta H$ and  $\Delta S$ when bromine gas gets adsorbed on charcoal?

• 3)

What happens when a solution of NaCl is added to Fe(OH)3 sol, explain? Write whether Fe(OH)3 sol is a multimolecular colloid or macromolecular colloid.

• 4)

Why are substances like platinum and palladium often used for carrying out electrolysis of aqueous solutions?

• 5)

What role does adsorption play in hetrogeneous catalysis?

#### CBSE 12th Standard Chemical Kinetics Two Marks Questions - by Archana Singh - Deoghar - View & Read

• 1)

In some cases it is found that a large number of colliding molecules have energy more than threshold energy but yet the reaction is slow.  Why?

• 2)

The rate constant for a reaction of zero order in A is 0.0030 mol L-1 s-1.  How long will it take for the initial concentration of A to fall from 0.10 M to 0.075 M?

• 3)

A reaction is second order with respect to a reactant 'A'.  How is the rate of this reaction altered if the concentration of 'A' is

(i) doubled?     (ii) reduced to half?

• 4)

At 300 K a certain reaction is 50% completed in 20 minutes.  At 350 K, the same reaction is 50% completed in 5 minutes.  Calculate the activation energy for the reaction.

• 5)

Time required to decompose SO2Cl2 to half of its initial amount is 60 minutes.  If the decomposition is a first order reaction, calculate the rate constant of the reaction.

#### CBSE 12th Chemistry - Electrochemistry Two Mark Questions - by Archana Singh - Deoghar - View & Read

• 1)

Determine the values of equilibrium constant (Kc) and $\triangle { G }^{ o }$ for the following reaction:

$Ni(s)+{ 2Ag }^{ + }(aq)\rightarrow { Ni }^{ 2+ }(aq)+2Ag(s)\\ { E }^{ o }={ 1.05V(1F=96500C\quad mol }^{ -1 })$

• 2)

What are fuel cells?How do they resemble and differ from galvanic cells?

• 3)

The same quantity of electrical charge deposited 0.583 g of Ag when passed through AgNO3, AuCl3 solution.Calculate the weight of gold formed. (At weight of Au=197 g mol-1).

• 4)

Solutions of two electrolytes A and B each having a concentration of 0.2 M have conductivities 2 x 10-2 and 4 x 10-4 S cm-1 respectively. Which will offer greater resistance to the flow of current and why ?

• 5)

Arrange the following metals in the order in which they displace each other from the solution of their salts : Al, Cu, Fe, Mg and Zn

#### 12th Standard CBSE Chemistry Solution Two Marks Questions - by Archana Singh - Deoghar - View & Read

• 1)

If N2 gas is bubbled through water at 293 K, how many millimoles of N2 gas would dissolve in 1 liter  of water? Assume that N2 exerts a partial pressure of 0.987 bar. Given Henry's law constant for N2 at 293 K is 76.48 kbar.

• 2)

What type of non-idealities are exhibited by cyclohexane-ethanol and acetone-chloroform mixture? Give reasons for your answer.

• 3)

The boiling point of a solution of urea in water is 100.13oC. Calculate the freezing point of  solution .(Kf and Kb for water are 1.86 K kg mol-1 and 0.52 K kg mol-1 respectively).

• 4)

Calculate the normal boiling point of a sample of sea water containing 3.5% of NaCl and 0.13% of MgCl2 by mass. Given Kb (water) = 0.52 K kg mol-1 (Mol. Wt. of NaCl =58.5 g mol-1. MgCl2 = 95g mpl-1)

#### CBSE 12th Chemistry The Solid State Two Marks Questions - by Archana Singh - Deoghar - View & Read

• 1)

In terms of band theory, what is the difference
(i) between a conductor and a semiconductor?
(ii) between a conductor and an insulator?

• 2)

How are the following properties of crystals affected by Schottky and Frenkel defects?
(i) Density
(ii) Electrical conductivity.

• 3)

Explain the following with suitable example:An n-type semiconductor.

• 4)

Solids can be classified into three types on the basis of their electrical conductivities.
(i) Name three types of solids classified on the basis of electrical conductivities.
(ii) How will you explain such classification based theory?

• 5)

The density of chromium metal is 7.2 g cm-3 . If the unit cell is cubic with edge length of 289 pm, determine the type of unit cell (simple, body centred or face centred) [Atomic mass of Cr = 52 a.m.u., N0 = 6.02 $\times$ 1023 mol-1 ].

#### 12th CBSE Chemistry - Polymers Book Back Questions - by Archana Singh - Deoghar - View & Read

• 1)

Rayon is  a

• 2)

Which of the following is a branched polymer?

• 3)

Natural rubber is a polymer of

• 4)

Which of the following is biodegradable polymer of polyamide class?

• 5)

Which of the following statements is not true about low density polythene?

#### 12th CBSE Chemistry - Biomolecules Book Back Questions - by Archana Singh - Deoghar - View & Read

• 1)

Which of the following is incorrect for glucose?

• 2)

The term anomer of glucose refers to

• 3)

Important constituent of cell wall is

• 4)

The helical structure of protein is stabilized by

• 5)

Vitamin A is

### CBSE Education Study Materials

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Chemistry 2019 - 2020 Academic Syllabus

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#### Tips to score good marks in CBSE Class 12 Chemistry - by Bala Jan 23, 2019 Jan 23, 2019

Chemistry is one of the subjects in which a student can score full marks just doing a little bit ...

#### Tips to score good marks in CBSE Class 12 Chemistry - by Bala Jan 12, 2019 Jan 12, 2019

Chemistry is one of the subjects in which a student can score full  marks just doing a littl...

#### CBSEStudy Material - Sample Question Papers with Solutions for Class 12 Session 2019 - 2020

Latest Sample Question Papers & Study Material for class 12 session 2019 - 2020 for Subjects Biology, Physics, Maths, Accountancy, Business Studies, Introductory Microeconomics and Macroeconomics, Economics, Computer Science in PDF form to free download [ available question papers ] for practice. Download QB365 Free Mobile app & get practice question papers.

More than 1000+ CBSE Syllabus Sample Question Papers & Study Material are based on actual Board question papers which help students to get an idea about the type of questions that will be asked in Class 12 Final Board Public examinations. All the Sample Papers are adhere to CBSE guidelines and its marking scheme , Question Papers & Study Material are prepared and posted by our faculty experts , teachers , tuition teachers from various schools in Tamilnadu.

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