The IE₁ and IE_II in kJ/mol of a few elements are given in the following table:

1. Which of the above element is likely to be alkali metal?
(A) P
(B) Q
(C) R
(D) S
2. Which of the above element is likely to be alkaline earth metal?
(A) P
(B) Q
(C) R
(D) S
3. Which of the above element is likely to be noble gas?
(A) P
(B) Q
(C) R
(D) S

Hydrocarbons are compounds of carbon and hydrogen only, obtained from coal and petroleum mainly which are major sources of energy. Hydrocarbons are classified as open chain, saturated (alkanes), unsaturated (alkenes and alkynes), cyclic (alicyclic) and aromatic based on structure.
Alkanes show conformational isomerism due to free rotation along C-C bond leading to staggered and eclipsed conformations of ethane. Staggered conformation is more stable. Alkenes show geometrical (Cis-trans) isomerism due to restricted rotation around carbon-carbon double bond. Benzene and benzenoid show aromatic character. They follow Huckel rule \((4 n+2) \pi\) electrons which must be delocalised. The presence of activating and deactivating groups decide the position of electrophile after electrophilic substitution. Polynuclear fused aromatic hydrocarbons have carcinogenic property. Benzene is prepared by polymerisation of ethyne and by heating sodium benzoate with soda lime.
(a) Why is staggered form of ethane more stable than eclipsed form?
(b) Out of T-butene and 2-butene which will show geometrical isomerism.
(c) Why is cis-2.-butene has higher boiling point than trans-2-butene?
(d) Why is cyclopentadienyl anion is aromatic?
(e) Why is -NO₂ group m-directing towards electrophilic substitution?
(f) Convert acetylene to benzene .
(g) Sodium benzoate, on heating with soda lime gives benzene, name the reaction.

Organic reactions can be classified into four main categories. Substitution reactions, addition reactions, elimination reactions and rearrangement reactions. Substitution reactions can be further classified into free radical, nucleophilic and electrophilic substitution reactions. Addition reactions can be nucleophilic as well as electrophilic addition reactions. Dehydration, dehydrohalogenation, dehalogenation are examples of elimination reactions. Conversion by ammonium cyanate to urea is an example of rearrangement reactions. Reactions are classified on the basis to nature of intermediate species formed. Mechanism of reaction is exact path followed by the reaction involving all steps showing intermediates and slowest steps of the reaction which is rate determining step. Oxidation, reduction, combustion reactions are also important in hydrocarbons.
(a) Halogenation of alkane is an example of which type of reaction?
(b) What happens when 2-methyl propane is heated with KMnO₄?
(c) What type of reaction takes place when n-hexane is heated in presence of AICI₃ (anhy.) and HCI?CH2 =CH2 + KCI + HzO
(d) What happens when but-2-yne reacts with H₂ in presence of Lindlar's catalyst.
(e) CH₃CH₂C1 + KOH(alc) \(\longrightarrow\) CH₂ =CH₂ + KCI + H₂O 
What is type of reaction?
(f) Why do aromatic hydrocarbons undergo electrophilic substitution reaction?

Organic compounds are formed by covalent bonding. The nature of covalent bonding can described with the help of hybridisation, sp, Sp² and sp³. The structure and reactivity depends upon type of bonds present in organic compounds. Organic compound can be represented by various structural formulae, Wedge and Dash formula is 3-D representation. Organic compounds can be classified on the basis of functional groups. Organic reactions mechanism are based on structure of substrate and the attacking reagent.
The intermediate formed can be free radical, carbocation, carbanion or carbene. The attacking reagent can be electrophile or nucleophile. The inductive, electromeric, resonance and hyper conjugative effect may help in polarisation of covalent bond. Organic reactions may be regarded as substitution, addition, elimination and rearrangement, oxidation and reduction reaction.
After the compound is obtained in pure state, qualitative analysis helps to detect elements present in organic compounds whereas quantitative analysis helps to find percentage of various elements. Dumas and Kjeldahl method help to determine percentage of nitrogen, Carius method for halogens and sulphur. Carbon and hydrogen are estimated by the amount of CO₂ and H₂Oformed. Phosphorus estimation is done by oxidising it to H₃ PO₄, sulphur to H₂ SO₄ , The percentage of oxygen is determined by taking the difference of 100 and percentage of all elements. Empirical formula gives simple ratios of elements whereas molecular formula gives exact number of atoms of each element present in a compound.
(a) What are free radicals?
(b) Write the order of stability of carbocation.
(c) An organic compounds has 8% sulphur. What is minimum molar mass of compound?
(d) If C is 75%, H = 25%, what is molecular formula of compound?
(e) In estimation of sulphur, which compound of sulphur is formed?
(f) f Lassaigne extract of organic compound give blood-red colour with FeCI₃, what does it show?
(g) Why should we add HNO₃ to Lassaigne extract before testing for halogens.

The order of decreasing priority of some functional groups is \(-\mathrm{COOH},-\mathrm{SO}_{3} \mathrm{H},-\mathrm{COOR},-\mathrm{COCl},-\mathrm{CONH}_{2}\), 

Observe the table based on different functional groups and their respective prefix and suffix given below and answer the questions as follow.

Functional Group	Prefix	Suffix
Alkane	-	- ane
Alkane	-	- ene
Alkane	-	- yne
-x	Halo (chloro, bromo, iodo)	-
-OH	Hydroxy	- ol
	Aldo or formyl	- al
	Oxo	- one
\(-\mathrm{C} \equiv \mathrm{N}\)	Cyano	nitrile
-ROR	Alkoxy	ether
-COOH	Carboxy	- oic acid
-COOR	Alkoxy carbonyl	- oate
-NH2	Amino	- amine
-NO2	Nitro	-
-CONH2	Carbamoyl or Amido	- amide
-COX	Halo formyl	- oyl halide
-SO3H	Sulpho	sulphonic acid

(a) Write IUPAC Dame of HOCH₂ -(CH₂ )₃-CH₂COCH₃ .
(b) What is IUPAC Dame of CH₂ =CH-CH₂Br. Give reason.
(c) What is IUPAC name of 
 (i) 
 
(ii) CH₂ =CH-CH=CH₂ 
(d) Write structural formula of 6-methyl ectan-s-ol.
(e) Write IUPAC name of
(i) 

(ii) 

(f) Write IUPAC name of 

(g) Write structural formula of cyclohex-2-en-1-ol.

It is essential to purify an organic compound. The method used for purification depends upon nature of compound and impurity present in it. The common methods to purify a solid is sublimation and crystallisation. Crystallisation is most common method applicable to most of solid organic compounds. Liquids are purified by simple distillation, fractional distillation, distillation under reduced pressure, steam distillation. Differential extraction is used to extract organic compound from aqueous solution. Chromatography is used to separate coloured substances from plants. Column chromatography, thin layer chromatography and partition chromatography are types of chromatography used for isolation and purification of organic compounds.
(a) Which method is used to purify camphor?
(b) How is unwanted colour from organic compounds removed?
(c) How is chloroform (Boiling point 334 K) and aniline (b.pt. 457 K) are separated? Why?
(d) Which is condensed first in fractionating column, vapours of higher boiling point liquid or lower boiling point liquid?
(e) How is glycerol purified?
(f) How is Aniline purified? Why?
(g) How are o-nitrophenol and p-nitrophenol separated? Why?

Observe the group shown in figure and answer the questions that follow based on the graph and related studied concepts.

(a) Which group elements have lowest ionisation enthalpy and why?
(b) Which group element have highest ionisation enthalpy and why?
(c) Why is ionisation enthalpy of Be more than B?
(d) Why does 'N' have higher ionisation enthalpy than O?

The atomic and ionic radii decrease with increase in atomic number along a period from left to right. Atomic size and ionic size increases down the group.
Ionisation enthalpy decreases down the group and increases along a period from left to right. It also depends upon shielding effect as well as stability of electronic configuration.
Electronegativity decreases down the group but increases along the period.
(a) Arrange the elements of second period in increasing order of first ionisation enthalpy.
(b) Arrange the elements of group 13 in increasing order of atomic size.
(c) Select the' amphoteric oxides among the following:
NO, B₂O₃, Cr ₂O₃, BeO, ZnO, CO₂ , Al₂ O₃
(d) For an element I.E₁ = 738 kJ mol^-1, IE₂ = 1450 kJ mol^-1, IE₃ = 7700 kJ mol^-1, IE₄ = 1.1 x 10 ⁴ kJ mol^-1. Name the main group to which element belong. Why?

Modern periodic table arranges the elements in the increasing order of atomic number. It has 18 groups and 7 periods. Atomic numbers are consecutive in a period and increases in group in a pattern. Elements are divided into four blocks, s-block,p-block, d-block andf-block based on their electronic configuration. 78% of elements are metals, about 20 elements are non-metals and few elements like B, Si, Ge, As are metalloids. Metallic character increases down the group but decreases along the period from left to right. The physical and chemical properties vary periodically with their atomic numbers.
Periodic trends are observed in atomic size, ionisation enthalpies, electron gain enthalpies, electronegativity and valence. Oxides of metals are basic, some are amphoteric. Non-metals form acidic oxides, some form neutral oxides. s-block elements are soft, highly reactive, do not show variable oxidation states. p-block elements are metals, non-metals as well as metalloids, show variable oxidation states, exist as solids, liquids and gases. d-block elements are metals, form coloured ions, show variable oxidation states, have high melting and boiling points. Lanthanoids and actinoids are f-block elements, form coloured ions. All actinoids are radioactive.
(a) Name the elements which belong to d-block but are not transition metals.
(b) What are representative elements?
(c) What is difference between oxidation states of p-block and d-block elements?
(d) Which group elements are most electropositive and why?
(e) What happens to reactivity down the group 17?
(f) What type of compounds are formed by element belonging to group 14 and third period? Identify the element.
(g) What is formula of compound formed between AI and S

Chemistry play an important role in human needs for food, health care products and improving life. Cis platin and taxol are used in chemotherapy, AZT (Azidothymidine) is used for AIDS. SI units are international units of measurement. Matter is classified into elements, compounds and mixtures, which can be homogeneous as well as heterogeneous. A mixture can be separated by physical methods, compounds can be separated by chemical methods only. Atomic mass is average of masses of isotopes depending upon their natural abundance. Empirical formula is calculated with the help of percentage composition of elements in a compound and molecular mass helps to calculate molecular formula. A chemical equation must be balanced so as to follow laws of chemical combination.
(a) Express 2.54 mm into S.I units.
(b) Out of milk, diamond, air, petrol which is pure substance?
(c) Balance the equation: NO₂ + H₂ O \(\rightarrow\) HNO₃ + NO
(d) What is percentage of Na in Na₂CO₃ ? (Na = 23u, C = 12, O = 16u)
(e) \({ }_{17}^{35} \mathrm{Cl} \text { and }{ }_{17}^{37} \mathrm{Cl}\) are in ratio of 3 : 1 in nature. What is atomic mass of CI?
(f) What is empirical formula of C₆H₁₂O₆?
(g) Chlorophyll contains 2.68% magnesium atoms. Calculate mass of magnesium atoms in 2 g of chlorophyll.

In the table given below to illustrate precision and accuracy. Study the table and answer the questions based on the table and related studied concepts.
Data to Illustrate Precision and Accuracy

(a) What is meant by precision?
(b) What is accuracy?
(c) If actual mass of a piece of metal is 0.520 g, data for which student is neither precise nor accurate.
(d) Which student data is precise but not accurate?
(e) The data of which student is both precise and accurate?
(f) How many significant figures are in 0.520?
(g) What is scientific notation for 0.520?

Stoichiometry is a section of chemistry that involves calculation based on chemical equations. Chemical equations are governed by laws of chemical combination. Mass of reactants is equal to mass of products. Compound obtained from different methods contain the same elements in the fixed ratio by mass. Mole is a counting unit, equal to 6.022 x 10²³ particles.
One mole is also equal to molar mass expressed in grams. One mole of every gas at STP has volume equal to 22.4 L. The reacting species which are consumed in the reaction completely is called limiting reagent which decides amount of products formed. Concentration of solution is expressed in terms of molarity, molality and mole fraction.
(a) Calculate number of moles of NH₃ formed by reaction of 2 moles of N₂ and 2 moles of H₂.
\(\mathbf{N}_{2}(g)+3 \mathbf{H}_{2}(g) \longrightarrow 2 \mathrm{NH}_{3}(g)\)
(b) Calculate number of electrons in 18 g of H₂ O. [Atomic number of H = 1 ,O = 8]
(c) Calculate the molality of 1 M NaCI solution having density 1.10 g cm^-3. (Molar mass = 58.5 g mol^-1)
(d) Define mole fraction.
(e) In aqueous solution of glucose X_glucose = 0.1, what is X_H2O = ?