$\mathrm{n}$-Propanol on treatment with concentrated $\mathrm{HBr}$ gives $\mathrm{P}$. The product $\mathrm{P}$ on reaction with $\mathrm{KCN}$ gave the product $\mathrm{Q}$. The product $\mathrm{Q}$ on heating with aqueous acidic solution, furnished the product $\mathrm{R}$. The product '$\mathrm{R}$' is

The major product of the following reaction is:

In the above reaction, the reagent "$A$" is :

The compound $\mathrm{X}$ in the following reaction scheme:

 is:

Consider the above chemical reaction and identify product $\mathrm{A}$

Considering the above chemical reaction, identify the product $\mathrm{X}:$

How will you bring about the following conversion:

Benzaldehyde to benzophenone?