Consider the following reactions.

$\underset{\text { (Hot solution) }}{\mathrm{PbCl}_2}+\mathrm{K}_2 \mathrm{CrO}_4 \rightarrow A+2 \mathrm{KCl}$

$$ \begin{aligned} & \mathrm{A}+\mathrm{NaOH} \rightleftharpoons \mathrm{~B}+\mathrm{Na}_2 \mathrm{CrO}_4 \\ & \mathrm{PbSO}_4+4 \mathrm{CH}_3 \mathrm{COONH}_4 \rightarrow\left(\mathrm{NH}_4\right)_2 \mathrm{SO}_4+\mathrm{X} \end{aligned} $$

In the above reactions, $\mathrm{A}, \mathrm{B}$ and X are respectively.

Given below are two statements :

Statement I : Among $\left.\left[\mathrm{Cu}\left(\mathrm{NH}_3\right)_4\right]^{2+},\left[\mathrm{Ni}(\mathrm{en})_3\right)\right]^{2+},\left[\mathrm{Ni}\left(\mathrm{NH}_3\right)_6\right]^{2+}$ and $\left[\mathrm{Mn}\left(\mathrm{H}_2 \mathrm{O}\right)_6\right]^{2+}$, $\left[\mathrm{Mn}\left(\mathrm{H}_2 \mathrm{O}\right)_6\right]^{2+}$ has the maximum number of unpaired electrons.

Statement II : The number of pairs among $\left\{\left[\mathrm{NiCl}_4\right]^{2-},\left[\mathrm{Ni}(\mathrm{CO})_4\right]\right\},\left\{\left[\mathrm{NiCl}_4\right]^{2-},\left[\mathrm{Ni}(\mathrm{CN})_4\right]^{2-}\right\}$ and $\left\{\left[\mathrm{Ni}(\mathrm{CO})_4\right],\left[\mathrm{Ni}(\mathrm{CN})_4\right]^{2-}\right\}$ that contain only diamagnetic species is two.

In the light of the above statements, choose the correct answer from the options given below :

An organic compound $(\mathrm{P})$ on treatment with aqueous ammonia under hot condition forms compound $(\mathrm{Q})$ which on heating with $\mathrm{Br}_2$ and KOH forms compound $(\mathrm{R})$ having molecular formula $\mathrm{C}_6 \mathrm{H}_7 \mathrm{~N}$. Names of P, Q and R respectively are.

$$ \text { From the following, the least stable structure is : } $$