Write the reaction of addition of $\mathrm{HCN}$ to ethyne.

Consider the following reaction:

The product $\left(\mathrm{Y}\right)$ is

The major product of the following reaction is

Which among the following depicts the correct order of acidity?

A, B and C respectively are

In the compound, 

$\underset{\left(\mathrm{I}\right)}{{\mathrm{CH}}_2}=\underset{\left(\mathrm{II}\right)}{\mathrm{CH}}-\mathrm{C}\underset{\left(\mathrm{III}\right)}{\equiv \mathrm{CH}}$

The most acidic hydrogen atom is

The major product in the following reactions is

${\mathrm{C}}_6{\mathrm{H}}_5-\mathrm{C}\equiv \mathrm{CH}\underset{\left(\mathrm{ii}\right)\mathrm{HI}\left(1\mathrm{eq}\right)}{\overset{\left(\mathrm{i}\right)\mathrm{HCl}\left(1\mathrm{eq}\right)}{\to }}$

In the reaction


$\mathrm{x}$ and $\mathrm{y}$ , respectively, are

The correct sequence of reagents for the following conversion will be