Which of the following complexes will show coordination isomerism?

A. $[\mathrm{Ag(NH}_3)_2][\mathrm{Ag(CN)}_2]$

B. $[\mathrm{Co(NH}_3)_6][\mathrm{Cr(CN)}_6]$

C. $[\mathrm{Co(NH}_3)_6][\mathrm{Co(CN)}_6]$

D. $[\mathrm{Fe(NH}_3)_6][\mathrm{Co(CN)}_6]$

E. $[\mathrm{Co(NH}_3)_6][\mathrm{Fe(CN)}_6]$

Choose the correct answer from the options given below:

Complete combustion of $X$ g of an organic compound gave $0.25$ g of $CO_2$ and $0.12$ g of $H_2O$. If the % of carbon is $25\%$ and of hydrogen is $4.89\%$, then $X = \underline{\phantom{xxx}} \times 10^{-3}$ g. (Nearest integer)

(Molar mass of C, H and O are 12, 1 and 16 g mol$^{-1}$ respectively.)

Given below are two statements :

Statement I : In , the carbocation is stabilised by +R effect of –OCH₃ group.

Statement II : In , the carbanion is stabilised by –R effect of –NO₂ group.

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

The compound (X) on

(i) on heating in the presence of anhydrous AlCl₃ and HCl gas gives 2,4-dimethyl pentane

(ii) aromatization gives toluene and

(iii) cyclisation gives methyl cyclohexane

The correct name of compound (X) is: