The major product $\left[\mathrm{X}\right]$ is:

The major product of the above reaction is obtained by mechanism.

$$\begin{gathered} \mathrm{A}+{\mathrm{PCl}}_{\mathrm{5}}\mathrm{ }\stackrel{}{\to }\mathrm{B} \\ \mathrm{B} \underset{\mathrm{ether}}{\overset{\mathrm{Na}}{\to }}\mathrm{n}-\mathrm{butane}. \end{gathered}$$

$\mathrm{A}$ and $\mathrm{B}$ are ______.

The acid produced $\left(\mathrm{A}\right)$ in the sequence given below is:

${\mathrm{C}}_2{\mathrm{H}}_5\mathrm{I} \stackrel{\mathrm{alc}. \mathrm{KOH}}{\to }\mathrm{X} \underset{{\mathrm{CCl}}_{\mathrm{4}}}{\stackrel{{\mathrm{Br}}_{\mathrm{2}}}{\to }}\mathrm{Y}\stackrel{\mathrm{KCN}}{\to }\mathrm{Z} \stackrel{{\mathrm{H}}_{\mathrm{3}}{\mathrm{O}}^{\mathrm{+}}}{\to }\mathrm{A}$

The isomer of ${\text{C}}_{\text{4}}{\text{H}}_{\text{9}}\text{I}$, which is capable of producing $\text{But-2-ene}$ with alcoholic $\text{KOH}$ solution is:

The compound, which is not formed when a mixture of $\mathrm{n}-\text{butyl bromide}$ and $\mathrm{ethyl} \mathrm{bromide}$ treated with $\mathrm{Na}$ metal in the presence of dry ether is _______.

In the reaction: $\mathrm{Propene}\stackrel{{\mathrm{Cl}}_2/500°\mathrm{C}}{\to }\mathrm{A}\stackrel{\mathrm{Na}}{\to }\mathrm{B}$, $\mathrm{B}$ is