$\mathrm{Si}$ reacts with ${\mathrm{CH}}_3\mathrm{Cl}$ at $573 \mathrm{K}$ in the presence of $\mathrm{Cu}$ powder to form methyl substituted chlorosilanes. Among the given methyl substituted chlorosilanes, whose yield is minimum?

Give the correct characteristic colours of the products $(\mathrm{P}, \mathrm{Q}, \mathrm{R}, \mathrm{S})$ formed in the following reactions.

A) $\mathrm{NO}+{\mathrm{NO}}_2\stackrel{<250 \mathrm{K}}{⟶}\mathrm{P}$

B) $2{\mathrm{NO}}_2⟷\mathrm{Q}$

C) $\mathrm{Pb}{\left({\mathrm{NO}}_3\right)}_2\stackrel{673 \mathrm{K}}{⟶}\mathrm{R}+\mathrm{PbO}$

D) ${\mathrm{HNO}}_3+{\mathrm{P}}_4{\mathrm{O}}_{10}⟶\mathrm{S}+4{\mathrm{HPO}}_3$

Identify the reactions in which ${\mathrm{N}}_2$ is liberated.

$\left(\mathrm{a}\right)$ ${\left({\mathrm{NH}}_4\right)}_2{\mathrm{SO}}_4+\mathrm{NaOH}⟶$

$\left(\mathrm{b}\right)$ ${\mathrm{NH}}_3+{\mathrm{Cl}}_2⟶$ (excess)

$\left(\mathrm{c}\right)$ ${\left({\mathrm{NH}}_4\right)}_2{\mathrm{Cr}}_2{\mathrm{O}}_7\stackrel{\mathrm{\Delta }}{⟶}$

$\left(\mathrm{d}\right)$ ${\mathrm{NH}}_4{\mathrm{NO}}_3\stackrel{\mathrm{\Delta }}{⟶}$

$\left(\mathrm{e}\right)$ ${\mathrm{NH}}_4{\mathrm{Cl}}_{\left(\mathrm{aq}\right)}+{\mathrm{NaNO}}_{2\left(\mathrm{aq}\right)}⟶$