(i) The monochlorination products obtained depends upon the kinds of hydrogen present in the molecule.

(ii) There are four different types of hydrogen in the molecule; $\mathrm{H}_a, \mathrm{H}_b, \mathrm{H}_c$ and $\mathrm{H}_d$.

IIT-JEE 2011 Paper 2 Offline Chemistry - Hydrocarbons Question 7 English Explanation 1

(iii) The monochlorination products obtained on replacement of these hydrogen are as follows :

(a) Replacing $\mathrm{H}_a$ with chlorine :

IIT-JEE 2011 Paper 2 Offline Chemistry - Hydrocarbons Question 7 English Explanation 2

Since, the carbon is a chiral; only one monochlorination isomer is possible when $\mathrm{H}_a$ is replaced by chlorine.

(b) Replacing $\mathrm{H}_b$ with chlorine :

IIT-JEE 2011 Paper 2 Offline Chemistry - Hydrocarbons Question 7 English Explanation 3

Since all the carbons are a chiral; only one monochlorination product is possible by when $\mathrm{H}_b$ replaced by Cl .

(c) Replacing $\mathrm{H}_c$ with chlorine

IIT-JEE 2011 Paper 2 Offline Chemistry - Hydrocarbons Question 7 English Explanation 4

The carbon on which hydrogen is replaced by chlorine becomes chiral; hence R/S isomers exist.

Also, carbon adjacent to the carbon on which hydrogen $\left(\mathrm{H}_c\right)$ is replaced, is also chiral; hence, it will also exist as a pair of enantiomer $R / S$ four monochlorination products (which are stereoisomers or optical isomers) are possible.

(d) Replacing $\mathrm{H}^d$ by chlorine :

IIT-JEE 2011 Paper 2 Offline Chemistry - Hydrocarbons Question 7 English Explanation 5

The central carbon $\left({ }^*\right)$ becomes chiral when $\mathrm{H}^d$ is replaced by chlorine; hence $R / S$ isomers exist. Two monochlorination products are possible (stereoisomers or optical isomers) are possible.

Total number of isomers possible are 8.