Explain Finkelstein reaction. 

Identify the reagent(s) '$\mathrm{A}$' and condition(s) for the reaction :

The major product of the following reaction is:

For the given reaction:

What is $\mathrm{A}$?

Major product P of above reaction, is:

The following reaction,

$\mathrm{R}-\mathrm{X}+\mathrm{NaI}\to \mathrm{R}-\mathrm{I}+\mathrm{NaX}$  where, $\mathrm{X}=\mathrm{Cl},\mathrm{Br}$ is known as

The major products, $\mathrm{P}$ and $\mathrm{Q}$, formed in the reactions given below are:

Identify $\mathrm{X}$ in the reaction given below

The major product (Q) of the below reactions is