MHTCET 17 Apr 2026 Shift 2 Paper

Concept:A carbon atom is chiral when it is bonded to four different groups.Explanation:Write the complete structure of 2-iodo-3,4,5-trimethylhexane:$$\mathrm{CH}_{3}-\mathrm{CH}(\mathrm{I})-\mathrm{CH}\left(\mathrm{CH}_{3}\right)-\mathrm{CH}\left(\mathrm{CH}_{3}\right)-\mathrm{CH}\left(\mathrm{CH}_{3}\right)-\mathrm{CH}_{3}$$Check each main-chain carbon atom for chirality.$\mathrm{C}_2$ is attached to $\mathrm{I}$, $\mathrm{H}$, $\mathrm{CH}_3$, and the rest of the carbon chain — all four groups are different, so it is chiral.$\mathrm{C}_3$ is attached to $\mathrm{H}$, $\mathrm{CH}_3$, the $\mathrm{C}_2$ side, and the $\mathrm{C}_4$ side — both sides are different chains, so it is chiral.$\mathrm{C}_4$ is attached to $\mathrm{H}$, $\mathrm{CH}_3$, the $\mathrm{C}_3$ side, and the $\mathrm{C}_5$ side — the two sides are different, so it is chiral.$\mathrm{C}_5$ is attached to $\mathrm{H}$, $\mathrm{CH}_3$, the $\mathrm{C}_4$ side, and another $\mathrm{CH}_3$ group — two identical $\mathrm{CH}_3$ groups are present, so it is not chiral.Hence, the chiral carbon atoms are $\mathrm{C}_2$, $\mathrm{C}_3$, and $\mathrm{C}_4$.Answer:Number of chiral carbon atoms = 3, which is Option B.