The product due to racemization is optically inactive because:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → two enantiomers in equal proportion are obtained
The two enantiomers of a chiral compound rotate plane polarised light by the same angle in opposite directions. Racemisation converts an enantiomer into an equimolar (50 : 50) mixture of the d and l forms, called a racemic mixture. The rotation caused by one form is cancelled by the other (external compensation), so the product shows zero optical rotation, although each molecule is still chiral. This happens, for example, in an SN1 reaction, where the nucleophile can attack the planar carbocation from either side.
Why the other options are incorrect
Option (1) an optically inactive compound is obtained — Incorrect. Each molecule formed is still chiral; the inactivity comes from the mixture, not from the compound.
Option (2) a compound with inversion of configuration is obtained — Incorrect. Complete inversion, as in an SN2 reaction, gives a single enantiomer, which is optically active.
Option (3) an enantiomer is obtained — Incorrect. A single enantiomer rotates plane polarised light.
NCERT (2026-27 edition):
Reactions of Haloalkanes – …
