The treatment of $CH_3MgX$ with $CH_3-C \equiv CH$ produces

To convert $1$-butyne to $1-D$-butanal,one would carry out the following steps :
$(I)$ Sodium amide,then $D_2O$
$(II)$ Disiamylborane,then hydrogen peroxide/sodium hydroxide
$(III)$ The transformation can not be carried out with the indicated reagents.

Which of the following reactions will yield $2, 2-$dibromopropane?

Write the following reactions:
$(1)$ Reaction of acetylene with $HCN$.
$(2)$ Hydrogenation of ethyne in the presence of Lindlar catalyst $(Pd, BaSO_4)$.

$1, 2$-Dibromopropane on treatment with $X$ moles of $NaNH_2$ followed by reaction with ethyl bromide gives $2$-pentyne. The value of $X$ is:

$CH_3-C \equiv C-CH_3 \, \xrightarrow[{(2) Br_2}]{{(1) H_2 /Pd/CaCO_3}} \, (X) \, , \, (X)$ is