21.

What is the cause of a feeling of depression in human beings? Name a drug which can be useful in treating this depression.

Explain the following behaviours:

(i) Alcohols are more soluble in water than the hydrocarbons of comparable molecular masses.

(ii) Ortho-nitro phenol is more acidic than ortho-methoxyphenol.

Explain the mechanism of acid catalysed hydration of an alkene to form corresponding alcohol.

Complete the following chemical reaction equations:

(i) C₆H₅N₂Cl + H₃PO₂+ H₂O --->

(ii) C₆H₅NH₂+ Br₂(aq.)--->

Describe the following giving the relevant chemical equation in each case:

(i) Carbylamines reaction

(ii) Hofmann’s bromamide reaction.

Differentiate between disinfectants and antiseptics. Give one example of each group.

Answer the following question:

(i) What is meant by the chirality of a compound? Give an example.

(ii) Which one of the following compounds is more easily hydrolyzed by KOH and why?

CH₃CHCICH₂CH₃ or CH₃CH₂CH₂Cl

(iii) Which one undergoes S N 2 substitution reaction faster and why?

Define the following as related to proteins:

(i) Peptide linkage

(ii) Primary structure

(iii) Denaturation

Differentiate between thermoplastic and thermosetting polymers. Give one example of each.

(a) Draw the molecular structure of the following compounds.

(i) N₂O₅

(ii) XeOF₄

(b) Explain the following observation:

(i) Sulphur has a greater tendency for catenation than oxygen.

(ii) ICI is more reactive than I₂.

(iii) Despite the lower value of its electron gain enthalpy with a negative sign, fluorine (F₂) is a stronger oxidizing agent than Cl₂.