The number of chiral compounds produced upon monochlorination of $2$ -methylbutane is:

In the following reactions

 the major product $X$ is

The major product formed in the following reaction is:

${\left({\mathrm{CH}}_3\right)}_2\mathrm{CH}-{\mathrm{CH}}_2{\mathrm{CH}}_3\stackrel{{\mathrm{Cl}}_2/\mathrm{hv}}{\to }\left[\mathrm{N}\right]\frac{\text{ Fractional }}{\text{ distillation }}\to \left[\mathrm{P}\right]$

Identify the total number of possible product in $\mathrm{N} \text{and} \mathrm{P}$ (by monochlorination).