${\mathrm{CoCl}}_2+{\mathrm{KNO}}_2+{\mathrm{CH}}_3\mathrm{COOH}⟶\left[\mathrm{X}\right]+{\mathrm{H}}_2\mathrm{O}+\mathrm{KCl}+{\mathrm{CH}}_3\mathrm{COOK}+\mathrm{NO}$ (Unbalanced equation).

Choose the correct statement about $\mathrm{X}$.

Here,

${\mathrm{Co}}^{2+}+7{\mathrm{NO}}_2^{-}+2{\mathrm{H}}^{+}+3{\mathrm{K}}^{+}⟶\underset{\stackrel{\mathrm{Yellow} \mathrm{ppt}.}{ }}{{\mathrm{K}}_3\left[\mathrm{Co}{\left({\mathrm{NO}}_2\right)}_6\right]}\downarrow +\mathrm{NO}\uparrow +{\mathrm{H}}_2\mathrm{O}$

                                                     $\left(\mathrm{X}\right) d^2\mathit{ }s{p}^3$ (inner orbital complex)

Thus, X is a yellow crystalline solid insoluble in water and an inner orbital complex.