MHTCET 15 May 2024 Shift 1 Paper

Concept:A molecule is chiral if it contains at least one carbon atom bonded to four different groups.Explanation:Consider each isomer of $\mathrm{C}_4\mathrm{H}_9\mathrm{Br}$: • n-Butyl bromide: $\mathrm{CH}_3\mathrm{CH}_2\mathrm{CH}_2\mathrm{CH}_2\mathrm{Br}$ – no carbon has four different groups. • sec-Butyl bromide: $\mathrm{CH}_3\mathrm{CH}(\mathrm{Br})\mathrm{CH}_2\mathrm{CH}_3$ – the second carbon is attached to $\mathrm{Br}$, $\mathrm{H}$, $\mathrm{CH}_3$, and $\mathrm{CH}_2\mathrm{CH}_3$, which are all different. • Isobutyl bromide: $(\mathrm{CH}_3)_2\mathrm{CH}\mathrm{CH}_2\mathrm{Br}$ – no chiral carbon, as two identical $\mathrm{CH}_3$ groups are present. • tert-Butyl bromide: $(\mathrm{CH}_3)_3\mathrm{CBr}$ – central carbon has three identical $\mathrm{CH}_3$ groups. Only sec-butyl bromide has a chiral centre and is optically active. Answer:Option B – sec-Butyl bromide.