Complete the reaction
`underset("But-2-yne")(CH_(3)-C-=C-CH_(3)) underset(H_(2))overset(Na//liq. NH_(3))to ?`

Explanation

To complete the reaction of but-2-yne with hydrogen in the presence of sodium and liquid ammonia, we can follow these steps:

### Step 1: Identify the Reactant
The reactant is but-2-yne, which has the structure:
\[ CH_3-C \equiv C-CH_3 \]
This means there is a triple bond between the second and third carbon atoms.

### Step 2: Understand the Reaction Conditions
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