The number of structural and configurational isomers of a bromo compound, `C_5H_9Br`, formed by the addition of `HBr` to 2-pentyne respectively, is:

Options

A. 1 and 2
B. 2 and 4
C. 4 and 2
D. 2 and 1

Answer

B

Explanation

Markovnikov's and anti-Markovnikov's addition of HBr gives two structural isomers, i.e., `CH_3C-=C CH_2CH_3 overset"HBr"to CH_3CH=C(Br)CH_2CH_3 + CH_3C(Br)=CHCH_2CH_3`
Each of these two isomers can exist as a pair of cis, trans-isomers and hence there are four configurational isomers.