Identify the major product of the following reaction:

Give chemical reactions for the following conversions:
$1$. $2-$bromobutane from $2-$butyne
$2$. $2-$propanol and $1-$propanol from propyne

$0.40 \, g$ of an organic compound $(A)$ with molecular formula $C_5H_8O$ reacts with $x$ moles of $CH_3MgBr$ to liberate $224 \, mL$ of a gas at $STP$. Upon hydrogenation with excess $H_2$,$(A)$ yields pentan-$1$-ol. The correct structure of $(A)$ is:

The major product of the following reaction is $P$. Number of oxygen atoms present in product $P$ is $. . . . . . . . . . . (nearest integer)$.

In the following reaction,compound $A$ is formed,which reacts with $B$ to give product $C$. Identify $A$ and $B$.

An unknown compound $X$ is an unsaturated hydrocarbon. It reacts with $HgSO_4$ and $H_2SO_4$ to give compound $(B)$. Compound $(B)$ on oxidation gives compound $(C)$. Compound $(C)$ on reaction with $NaOH$ and soda lime gives methane. Identify $A$ (which is $X$),$B$,and $C$ by providing the chemical reactions.