12th Standard Chemistry English Medium Important 1 Mark Book Back Questions (New Syllabus) 2020

Download Tamil Nadu 12th Standard Chemistry question papers, model tests, one-mark questions, important questions, and public exam papers in PDF format. Free study materials and answer keys for TN State Board students.

Questions:

Multiple Choice Question

33 x 1 = 33

Drugs that bind to the receptor site and inhibit its natural function are called _______.

(a)

antagonists

(b)

agonists

(c)

enzymes

(d)

molecular targets

Antiseptics and disinfectants either kill or prevent growth of microorganisms. Identify which of the following statement is not true.

(a)

dilute solutions of boric acid and hydrogen peroxide are strong antiseptics.

(b)

Disinfectants harm the living tissues

(c)

A 0.2% solution of phenol is an antiseptic while 1% solution acts as a disinfectant

(d)

Chlorine and iodine are used as strong disinfectants

The correct statement regarding RNA and DNA respectively is ______.

(a)

the sugar component in RNA is an arabinos and the sugar component in DNA is ribose

(b)

the sugar component in RNA is 2’-deoxyribose and the sugar component in DNA is arabinose

(c)

the sugar component in RNA is an arabinose and the sugar component in DNA is 2’-deoxyribose

(d)

the sugar component in RNA is ribose and the sugar component in DNA is 2’-deoxyribose

The product formed by the reaction an aldehyde with a primary amine ________.

(a)

carboxylic acid

(b)

aromatic acid

(c)

schiff ’s base

(d)

ketone

Aniline + benzoylchloride \(\overset { NaOH }{ \longrightarrow } \)C₆H₅ - NH - COC₆ H₅ this reaction is known as ______.

(a)

Friedel – crafts reaction

(b)

HVZ reaction

(c)

Schotten – Baumann reaction

(d)

none of these

In which of the following reactions new carbon – carbon bond is not formed?

(a)

Aldol condensation

(b)

Friedel craft reaction

(c)

Kolbe’s reaction

(d)

Wolf kishner reduction

The reagent used to distinguish between acetaldehyde and benzaldehyde is _______.

(a)

Tollens reagent

(b)

Fehling’s solution

(c)

2,4 – dinitrophenyl hydrazine

(d)

semicarbazide

Predict the product Z in the following series of reactions Ethanoic acid \(\overset { { PCI }_{ 5 } }{ \longrightarrow } X\overset { { C }_{ 6 }{ H }_{ 6 } }{ \underset { Anhydrous \ AlCI }-_{3}{ \longrightarrow } } Y\overset { 1){ CH }_{ 3 }MgBr }{ \underset { II){ H }_{ 3 }{ O }^{ + } }{ \longrightarrow } } Z.\)

(a)

(CH₃)₂ C(OH)C₆H₅

(b)

CH₃CH(OH)C₆H₅

(c)

CH₃CH(OH)CH₂- CH₃

(d)

Williamson synthesis of preparing dimethyl ether is a / an ______.

(a)

SN¹ reactions

(b)

SN² reaction

(c)

electrophilic addition

(d)

electrophilic substitution

10.

In the reaction Ethanol \(\overset { { PCl }_{ 5 } }{ \longrightarrow } X\overset { alc.KOH }{ \longrightarrow } Y\overset { { H }_{ 2 }{ SO }_{ 4 }/{ H }_{ 2 }O }{ \underset { 298k }{ \longrightarrow } } Z.\) The ‘Z’ is ______.

(a)

ethane

(b)

ethoxyethane

(c)

ethylbisulphite

(d)

ethanol

11.

Which of the following compounds on reaction with methyl magnesium bromide will give tertiary alcohol.

(a)

benzaldehyde

(b)

propanoic acid

(c)

methyl propanoate

(d)

acetaldehyde

12.

Match the following

a	V₂O₅	i	High density polyethylene
b	Ziegler – Natta	ii	PAN
c	Peroxide	iii	NH₃
d	Finely divided Fe	iv	H₂SO₄

(a)

A	B	C	D
iv	i	ii	iii

(b)

A	B	C	D
i	ii	iv	iii

(c)

A	B	C	D
ii	iii	iv	i

(d)

A	B	C	D
iii	iv	ii	i

13.

Statement : To stop bleeding from an injury, ferric chloride can be applied. Which comment about the statement is justified?

(a)

It is not true, ferric chloride is a poison.

(b)

It is true, Fe³⁺ ions coagulate blood which is a negatively charged sol

(c)

It is not true; ferric chloride is ionic and gets into the blood stream.

(d)

It is true, coagulation takes place because of formation of negatively charged sol with Cl^-.

14.

Conductivity of a saturated solution of a sparingly soluble salt AB (1:1 electrolyte) at 298K is 1.85 ×10⁻⁵ S m⁻¹. Solubility product of the salt AB at 298K (Λ^o_m)_AB = 14 ×10⁻³S m² mol⁻¹.

(a)

5.7 x 10^-12

(b)

1.32 x 10⁻¹²

(c)

7.5 x 10⁻¹²

(d)

1.74 x 10^-12

15.

The button cell used is watches function as follows
Zn (s) + Ag₂O (s) + H₂O (l) ⇌ 2Ag (s) + Zn²⁺ (aq) + 2OH^-(aq) the half cell potentials are Ag₂O (s) + H₂O (l) + 2e^- → 2Ag (s) + 2OH^- (aq) E^o= 34V and Zn (s) → Zn²⁺ (aq) + 2e⁻ E⁰ = 0.76V . The cell potential will be_______.

(a)

0.84V

(b)

1.34V

(c)

1.10V

(d)

0.42V

16.

The solubility of BaSO₄ in water is 2.42 × 10^-3gL^-1 at 298K. The value of its solubility product(K_sp) will be (Given molar mass of BaSO₄ =233g mol^-1)

(a)

1.08 × 10^-14mol²L^-2

(b)

1.08 × 10^-12mol²L^-2

(c)

1.08 × 10^-10mol²L^-2

(d)

1.08 × 10^-8mol²L^-2

17.

If ‘a’ is the length of the side of the cube, the distance between the body centered atom and one corner atom in the cube will be_________.

(a)

\(\left( \cfrac { 2 }{ \sqrt { 3 } } \right) a\)

(b)

\(\left( \cfrac { 4 }{ \sqrt { 3 } } \right) a\)

(c)

\(\left( \cfrac { \sqrt { 3 } }{ 4 } \right) a\)

(d)

\(\left( \cfrac { \sqrt { 3 } }{ 2 } \right) a\)

18.

For a first order reaction A ⟶ product with initial concentration x mol L^-1, has a half life period of 2.5 hours. For the same reaction with initial concentration \(\left( \frac { x }{ 2 } \right) \) mol L^-1 the half life is

(a)

(2.5 x 2) hours

(b)

\(\left( \frac { 2.5 }{ 2 } \right) \) hours

(c)

2.5 hours

(d)

Without knowing the rate constant, t_1/2 cannot be determined from the given data

19.

The number of unit cells in 8 gm of an element X (atomic mass 40) which crystallizes in bcc pattern is (N_A is the Avogadro number)________.

(a)

6.023 x 10²³

(b)

6.023 x 10²²

(c)

60.23 x 10²³

(d)

\(\left( \frac { 6.023\times { 10 }^{ 23 } }{ 8\times 40 } \right) \)

20.

Solid CO₂ is an example of ________.

(a)

Covalent solid

(b)

metallic solid

(c)

molecular solid

(d)

ionic solid

21.

Which kind of isomerism is possible for a complex [Co(NH₃)₄Br₂]CI?

(a)

geometrical and ionization

(b)

geometrical and optical

(c)

optical and ionization

(d)

geometrical only

22.

Oxidation state of Iron and the charge on the ligand NO in [Fe(H₂O)₅NO]SO₄ are_______.

(a)

+2 and 0 respectively

(b)

+3 and 0 respectively

(c)

+3 and -1 respectively

(d)

+1 and +1 respectively

23.

An excess of silver nitrate is added to 100ml of a 0.01M solution of Pentaaquachlorochromium (III)chloride. The number of moles of AgCl precipitated would be _______.

(a)

0.02

(b)

0.002

(c)

0.01

(d)

0.2

24.

Which one of the following statements related to lanthanons is incorrect?

(a)

Europium shows +2 oxidation state

(b)

The basicity decreases as the ionic radius decreases from Pr to Lu.

(c)

All the lanthanons are much more reactive than aluminium

(d)

Ce⁴⁺ solutions are widely used as oxidising agents in volumetric analysis.

25.

MnO₄^- react with Br^- in alkaline P^H to give ________.

(a)

BrO₃^- MnO₂

(b)

Br₂, MnO₄^2-

(c)

Br₂, MnO₂

(d)

BrO^-, MnO₄^2-

26.

Which of the following compounds is colourless?

(a)

Fe³⁺

(b)

Ti⁴⁺

(c)

Co²⁺

(d)

Ni²⁺

27.

Which of the following d block element has half filled penultimate d sub shell as well as half filled valence sub shell?

(a)

(b)

(c)

(d)

none of these

28.

Duralumin is an alloy of ______.

(a)

Cu, Mn

(b)

Cu, Al, Mg

(c)

Al, Mn

(d)

Al, Cu, Mn, Mg

29.

On hydrolysis, PCl₃ gives________.

(a)

H₃PO₃

(b)

PH₃

(c)

H₃PO₄

(d)

POCl₃

30.

The basic structural unit of silicates is _______.

(a)

\(\left( SiO_{ 3 } \right) ^{ 2- }\)

(b)

\(\left( SiO_{ 4 } \right) ^{ 2- }\)

(c)

\(\left( Sio \right) ^{ - }\)

(d)

\(\left( SiO_{ 4 } \right) ^{ 4- }\)

31.

Which of the following metals has the largest abundance in the earth’s crust?

(a)

Aluminium

(b)

Calcium

(c)

Magnesium

(d)

Sodium

32.

Which one of the following is not feasible

(a)

Zn_(s) + Cu²⁺_(aq) \(\rightarrow\) Cu_(s) + Zn²⁺_(aq)

(b)

Cu_(s)+ Zn²⁺_(aq)\(\rightarrow\) Zn_(s) + Cu²⁺_(aq)

(c)

Cu_(s) + 2Ag⁺_(ag)\(\rightarrow\) 2Ag_(s) + Cu²⁺_(aq)

(d)

Fe_(s) + Cu²⁺_(aq) \(\rightarrow\) Cu_(s)+ Fe²⁺_(aq)

33.

Which one of the following reaction represents calcinations?

(a)

\(2Zn+{ O }_{ 2 }\rightarrow 2ZnO\)

(b)

\(2ZnS+3O_{ 2 }\rightarrow 2ZnO+2SO_{ 2 }\)

(c)

\(MgCO_{ 3 }\rightarrow MgO+CO_{ 2 }\)

(d)

Both (a) and (c)

Assertion and reason

3 x 2 = 6

34.

Assertion: A solution of sucrose in water is dextrorotatory. But on hydrolysis in the presence of little hydrochloric acid, it becomes levorotatory.
Reason: Sucrose hydrolysis gives unequal amounts of glucose and fructose. As a result of this change in sign of rotation is observed.
Codes:
a) If both accretion and reason are true and reason is the correct explanation of assertion.
b) If both assertion and reason are true but reason is not the correct explanation of assertion.
c) If assertion is true but reason is false.
d) if both assertion and reason are false.

(a)

If both accretion and reason are true and reason is the correct explanation of assertion

(b)

If both assertion and reason are true but reason is not the correct explanation of assertion

(c)

If assertion is true but reason is false.

(d)

if both assertion and reason are false.

35.

Assertion: Rate of reaction doubles when the concentration of the reactant is doubles if it is a first order reaction.
Reason: Rate constant also doubles
Codes:
a) Both assertion and reason are true and reason is the correct explanation of assertion.
b) Both assertion and reason are true but reason is not the correct explanation of assertion.
c) Assertion is true but reason is false
d) Both assertion and reason are false.

(a)

Both assertion and reason are true and reason is the correct explanation of assertion.

(b)

Both assertion and reason are true but reason is not the correct explanation of assertion.

(c)

Assertion is true but reason is false

(d)

Both assertion and reason are false.

36.

Assertion: Bond dissociation energy of fluorine is greater than chlorine gas
Reason: Chlorine has more electronic repulsion than fluorine.
Codes:
a) Both assertion and reason are true and reason is the correct explanation of assertion.
b) Both assertion and reason are true but reason is not the correct explanation of assertion
c) Assertion is true but reason is false
d) Both assertion and reason are false

(a)

Both assertion and reason are true and reason is the correct explanation of assertion.

(b)

Both assertion and reason are true but reason is not the correct explanation of assertion

(c)

Assertion is true but reason is false

(d)

Both assertion and reason are false

Visit QB365-SLMS - https://www.qb365.in/slms/

Answers Key:

Multiple Choice Question

33 x 1 = 33

(a)
antagonists

(a)
dilute solutions of boric acid and hydrogen peroxide are strong antiseptics.

(d)
the sugar component in RNA is ribose and the sugar component in DNA is 2’-deoxyribose

(d)
Wolf kishner reduction

(b)
Fehling’s solution

(b)
SN² reaction

10.

11.

12.

(a)

A B C D

iv i ii iii

13.

(b)
It is true, Fe³⁺ ions coagulate blood which is a negatively charged sol

14.

For 1:1 electrolyte K_sp = S²
\(=[\frac{ K \times 10^{-3}}{Λ^o}]^2\)
\(=[\frac{1.85 \times 10^{-5} \times 10^{-3}}{14 \times 10^{-3}}]^2\)
= (0.1321 x 10^-3)²
= 0.01745 x 1010^-10
= 1.74 x 10^-12

15.

Anodic Oxidation: (Reverse the given reaction)
(E^o_ox) = 0.76 V Cathodic reduction
E^o_cell= (E^o_ox)+ (E^o_red)
= 0.76 + 0.34 = 1.1 V

16.

BaSO₄ ⇌ Ba²⁺ + SO₄^2-
K_sp = (s) (s)
K_sp = (s)²
= (2.42 × 10^-3gL^-1)²
\(=\frac{2.42 \times 10^{-3} gL^{-1}}{233 \text{ g mol}^{-1}}\)
= (0.01038 x 10^-3)²
= (1.038 x x 10^-5)²
= 1.077 x 10^-10
= 1.08 × 10^-10mol²L^-2

17.

If a is the length of the side, then the length of the leading diagonal passing through the body centered atom is \(\sqrt{3a} \)
Required distance = \(\left( \cfrac { \sqrt { 3 } }{ 2 } \right) a\)

18.

For a first order reaction
t_1/2 = \(\frac { 0.693 }{ { k }}\)
t_1/2 does not depend on the initial concentration and it remains constant (whatever may be the initial concentration)
t_1/2 = 2.5 hrs

19.

In bcc unit cell,
2 atoms = 1 unit cell
Number of atoms in 8 g of element is, Number of moles = 8g / 40 g mol^-1 = 0.2 mol
1 mole contains 6.023 x10²³ atoms
0.2 mole contains 0.2 x 6.023 x 10²³ atoms
[1 unit cell / 2 atoms] x 0.2 x 6.023 x 10²³
= 6.023 x 10²² unit cells.

20.

Lattice points are occupied by CO₂ molecules

21.

For [MA₄B₂]⁴⁺ complexes - geometrical isomerism is possible
{[Co(NH₃)₄Br₂]CI,[Co(NH₃)₄Br CI]Br} - ionisation isomers

22.

[\( \overset{+}{Fe}\)(H₂O)₅\( \overset{+}{NO}\)]²⁺ SO^2-₄
+1 and +1 respectively

23.

The complex is [M(H₂O)₅Cl]Cl₂
1000 ml of 1 M solution of the complex gives 2 moles of Cl^- ions 1000 ml of 0.01 M solution of the complex will give
\(\frac{100 ml \times 0.01M \times 2Cl^-}{1000 ml \times 1M}\)
= 0.002 moles of Cl^- ions

24.

As we move from La to Lu, their metallic behaviour because almost similar to that of aluminium.

25.