When but-1-yne reacts with two equivalents of `HBr`, the major product is

Options

A. `CH_(3)CH_(2)underset(Br)underset(|)(C)Hunderset(Br)underset(|)(C)H_(2)`
B. `CH_(3)CH_(2)CH_(2)CHBr_(2)`
C. `CH_(3)CH_(2)CBr_(2)CH_(3)`
D. `CH_(3)underset(Br)underset(|)(C)Hunderset(Br)underset(|)(C)HCH_(2)`

Answer

C

Explanation

It is a Markovnikov's electrophilic addition: The markovnikov addition of `H^(+)` to `CH_3CH_2CBr=CH_2` gives a carbocation that is stabilized by the inductive effect of the alkyl (R) group, as is the case with alkenes. But a much more significant stabilization occurs by extended `pi` bonding with Br.