Chemistry NCERT Exemplar Solutions Class 11th Chapter Twelve

13. Electronegativity of an element is directly proportional to its  s-character. If C is sp3hybridized then s- character is 25%, if it is sp2 hybridized then s-character is 33% and if sp hybridized then s-character is 50%. Hence, sp hybridized carbon has strong hybridization, s electrons are more strongly attracted by nucleus than p-electrons thus electronegativity of carbon increases with increase in s-character.

12. The given structure is of C₃H₄ in which all three carbon atoms are linked to each other by double bonds. Carbons are marked as Cl,  C₂ and C₃. Cl and C₃ are sp₂ hybridized as containing 3σ bonds and 1π bond. C₂ has 2 σ bonds and 2 π bonds so, it is sp hybridized.

11. Elements such as nitrogen, halogens, Sulphur, and phosphorus present in an organic compound converted into ions by fusing with sodium metal followed by plucking in distilled water getting sodium extract (Lassaigne's test). On adding dil. H₂SO₄ in place of dil. HNO₃for testing halogens by AgNO₃, white precipitate of AgSO₄ is formed. This will lead wrong result of chloride. Hence, only HNO₃ is used instead of dil. H₂SO₄

10. If two or more compounds have the same molecular formula but different carbon skeletons then these compounds are referred to as chain isomers and the phenomenon is termed as chain isomerism. The pairs of compounds that represent chain isomerism are- I, II, III, IV.

9. If two or more compounds differ in the position of substituent, functional group, or multiple bonds but molecular formula is same then these are said to be position isomers as they exhibit position isomerism. 

In the given structures, I and II, III and IV, VI and VII are found to be the position isomers.

8. The compounds with the same molecular formula but different functional groups are said to be functional group isomers. 

Alcohols are found to be the functional isomers of ether. In the given structures, I, II, III, IV  alcohol functional group is present and V, VI, VII contains ether functional group. Hence, I and V, I and VI, I and VII, II and V, II and VI, II and VII, III and V, III and VI etc. are functional group isomers.

7. If two or more compounds have the same molecular formula but different alkyl groups on either side of the functional groups then the compounds are said to be metamers. 

In the given structures- 

V and VI and VI and VII form a pair of metamers because alkyl groups are different on either side of the functional groups. 

6. Steam distillation is a special type of separation technique for temperature sensitive materials such as natural organic compounds. Few organic compounds tend to decompose at higher temperatures and normal distillation does not fit for this purpose. So, water is added to the apparatus and the temperature of the compounds is depressed, evaporating them at lower temperature. Once the distillation is accomplished, the vapours are condensed and  there occurs,   the separation of the constituents at ease.

4. Liquids which have different boiling points vaporize at different temperatures. The vapours are cooled and then liquids so formed are collected separately. Liquid A can be separated from B and C due to the large difference in boiling points. Liquid B and Liquid C have boiling points very close to each other and cannot be separated by simple distillation and are separated by fractional distillation. Liquid B distilled first since the order of boiling points of A, B and C is as follows: B < C < A.