Q.C5H13N reacts with HNO2 to give an optically active compound. The compound is

Step 1. C5H13N, a saturated 5-carbon amine, can be pentan-1-amine, pentan-2-amine (both primary), or a tertiary amine such as N,N-dimethylpropan-2-amine or diethylmethylamine.

Step 2. A PRIMARY amine + HNO2 gives an unstable diazonium salt that loses N2, replacing -NH2 with -OH at essentially the same carbon -- so the product's stereochemistry mirrors the starting amine's.

Step 3. Pentan-1-amine's amine-bearing carbon (C1, a CH2) is bonded to two identical hydrogens -- not a stereocentre -- so its alcohol product (pentan-1-ol) is achiral, not optically active. …

For each candidate amine, check (i) whether it is primary (able to undergo the diazonium-to-alcohol pathway at all) and (ii) whether its amine-bearing carb …

• Picking pentan-1-amine just because it is also a primary amine that reacts with HNO2 -- its amine carbon (a plain CH2) has two identical hydrogens and is not a stereocentr …