The major product formed in the following reaction is

Which of the following reagents will be able to distinguish between $but-1-yne$ and $but-2-yne$?

The product obtained in this reaction is:

The product$(s)$ obtained via oxymercuration $(HgSO_4 + H_2SO_4)$ of $but-1-yne$ would be

In the reaction
$HC \equiv CH \xrightarrow[(ii) CH_3CH_2Br]{(i) NaNH_2 / liq. NH_3} X$
$\xrightarrow[(ii) CH_3CH_2Br]{(i) NaNH_2 / liq. NH_3} Y$
$X$ and $Y$ are

Identify the compound $(Z)$ in the following reaction sequence: $CH_3-CH(Br)-CH_2Br$ $\xrightarrow{alc. KOH, \Delta}$ $\xrightarrow{NaNH_2}$ $\xrightarrow{H_2O, Hg^{2+}, H^+} (Z)$