$CH_3-C \equiv C-CH_3$ $\xrightarrow{NaNH_2}$ $X$. What is $X$?

The major products $P$ and $Q$ in the following reactions,respectively,are:
$H_3C-C \equiv C-CH_2CH_3 \xrightarrow{H_2, \text{Lindlar's Catalyst}} P$
$H_3C-C \equiv C-CH_2CH_3 \xrightarrow{Na/\text{liquid } NH_3} Q$

Which of the following will produce a chiral molecule after treatment with $H_2$/Lindlar's catalyst?

$CH_3-C \equiv C-CH_3 \xrightarrow{\text{Cold } KMnO_4} (A)$
Product $(A)$ is:

Which of the following has acidic hydrogen?

An unknown compound $(A)$ has a molecular formula $C_4H_6$. When $(A)$ is treated with excess of $Br_2$, a new substance $(B)$ with formula $C_4H_6Br_4$ is formed. $(A)$ forms a white precipitate with ammoniacal silver nitrate solution. $(A)$ may be: