When acetylene is passed through a red-hot iron tube, a compound $\mathrm{X}$ is formed. Which one of the following reactions will yield $\mathrm{X}$ as the major product?

In the following reactions

$\mathrm{X}$ and $\mathrm{Y}$, respectively, are:

The major product of the following reaction is:

Identify the product $\mathrm{X}$ obtained in following reaction

${\mathrm{CH}}_3-{\left({\mathrm{CH}}_2\right)}_4-{\mathrm{CH}}_3\underset{773 \mathrm{K}, 10-20 \mathrm{atm}}{\overset{{\mathrm{Cr}}_2{\mathrm{O}}_3}{\to }} \mathrm{X}$

Among the following, the reaction that proceeds through an electrophilic substitution, is:

The major product of the following reaction is:

${\mathrm{CH}}_2=\mathrm{CHBr}\underset{\mathrm{Red} \mathrm{hot} \mathrm{iron} \mathrm{tube}, 873 \mathrm{K}}{\overset{{\mathrm{NaNH}}_2}{\to }}\mathrm{P}$