Which of the following most accurately describes the first step in the reaction of hydrogen chloride with $1$-butene?

To carry out the given conversions,select the correct option.

Give the reactions for the following conversions:
$1$. Polyvinyl chloride from ethyne
$2$. Methane from propyne
$3$. $2,3-$Dimethylbutane from propene

The dibromo compound $[P]$ (molecular formula : $C_{9}H_{10}Br_{2}$) when heated with excess sodamide followed by treatment with dilute $HCl$ gives $[Q]$. On warming $[Q]$ with mercuric sulphate and dilute sulphuric acid yields $[R]$ which gives positive Iodoform test but negative Tollen's test. The compound $[P]$ is:

Which of the following is not used to distinguish ethene from ethane?

The product $(C)$ of the reaction is: