Which kind of isomerism is shown by the complex $\left[\mathrm{Co}{\left({\mathrm{NH}}_3\right)}_5\left(\mathrm{ONO}\right)\right]{\mathrm{SO}}_4?$

(P) Ionisation isomerism

 (Q) Linkage isomerism 

(R) Geometrical isomerism

 (S) Optical isomerism

${\mathrm{NO}}_2^{-}$ is an ambidentate ligand that can connect to a central metal ion via N or O. As a result, it exhibits linkage isomerism.

Between the coordination and ionisation spheres, there is an exchange of ${\mathrm{NO}}_2^{-}$and ${\mathrm{SO}}_4^{2-}$. As a result, it exhibits ionisation isomerism.

Because $M{a}_{5}b$ has only one form, it does not exhibit geometrical isomerism.

Because $M{a}_{5}b$ has a mirror plane, it does not exhibit optical isomerism.

$\left[\mathrm{M}{a}_{5}b\right]$ does not show GI and OI.

The correct answer is C.