Problem
The hydrocarbon which can react with sodium in liquid ammonia is
(1) $\ce{CH3CH2CH2C#CCH2CH2CH3}$
(2) $\ce{CH3CH2C#CH}$
(3) $\ce{CH3CH=CHCH3}$
(4) $\ce{CH3CH2C#CCH2CH3}$
Solution
Solve it as a case of terminal alkynes, otherwise all alkynes react with sodium in liquid ammonia.
Question
I know sodium in liquid ammonia is used to produce trans-alkenes from alkynes. But from the options, it seems all of them react with sodium in liquid ammonia.
The solution doesn't make any sense to me. If all of the alkynes given react with sodium in liquid ammonia, then why the question? And what difference does it make if the alkyne is terminal?