(D) The first molecule is $1$-bromo-$1$-chloro-butane (or a derivative with a $CH_2Cl$ group attached to the chiral center). The second molecule has a

Name: Exam Paper Generator | JEE NEET Paper Generator | Vedclass
Brand: Vedclass
Rating: 5 (35 reviews)

(D) The first molecule is $1$-bromo-$1$-chloro-butane (or a derivative with a $CH_2Cl$ group attached to the chiral center). The second molecule has a different carbon chain length attached to the chiral center (a $CH_2CH_2Cl$ group). Since the connectivity of the atoms is different,they are constitutional isomers.