CGPET 2019 Solved Paper

Key Point The carbon, which is bonded with four different atoms/groups is known as chiral carbon. The structure of the given IUPAC names are as follows: (a) 3 -methylhexane $\overset{6}{\mathrm{CH}_3}-\overset{5}{\mathrm{CH}_2}-\overset{4}{\mathrm{CH}_2}-\overset{3}{\mathrm{CH}}\underset{\mathrm{CH}_3}{\vert}$ $-\overset{2}{\mathrm{CH}_2}-\overset{1}{\mathrm{CH}_3}$ or $\mathrm{C}_3\mathrm{H}_7-^{•}\overset{\mathrm{H}}{\overset{\vert}{\mathrm{C}}}\underset{\mathrm{CH}_3}{\vert}-\mathrm{C}_2\mathrm{H}_5$ (It has one chiral carbon atom, marked with dot.) (b) 2 -methylhexane $\overset{6}{\mathrm{H}_3\mathrm{C}}-\overset{5}{\mathrm{CH}_2}-\overset{4}{\mathrm{CH}_2}-\overset{3}{\mathrm{CH}_2} - \overset{2}{\overset{\mathrm{H}}{\overset{\vert}{\mathrm{C}}}\underset{\mathrm{CH}_3}{\vert}} - \overset{1}{\mathrm{CH}_3}$ $\overset{5}{\mathrm{H}_3\mathrm{C}} - \overset{4}{\mathrm{CH}}\underset{\mathrm{CH}_3}{\vert} - \overset{3}{\mathrm{CH}_2} - \overset{2}{\mathrm{CH}}\underset{\mathrm{CH}_3}{\vert} - \overset{1}{\mathrm{CH}_3}$ It has no chiral carbon atom. (c) 2, 4-dimethyl pentane $\overset{5}{\mathrm{H}_3\mathrm{C}} - \overset{4}{\mathrm{CH}_2} - \overset{3}{\mathrm{CH}_2} - \overset{2}{\mathrm{CH}}\underset{\mathrm{CH}_3}{\vert} - \overset{1}{\mathrm{CH}_3}$ It has also no chiral carbon atom. (d) 2 -methyl pentane $\overset{5}{H_3C} -\overset{4}{CH_2}-\overset{3}{CH_2}-\overset{CH_3}{\underset{2}{CH}}-\overset{1}{CH_3}$ It has also no chiral carbon atom. Thus, option (a) is the correct answer.