The transition metal ions responsible for colour in ruby and emerald are, respectively:

Which kind of isomerism is exhibited by octahedral $\left[\mathrm{Co}{\left({\mathrm{NH}}_3\right)}_4{\mathrm{Br}}_2\right]\mathrm{Cl}?$

The $\mathrm{IUPAC}$ name of $\left[\mathrm{Ni}{\left({\mathrm{NH}}_3\right)}_4\right]\left[{\mathrm{NiCl}}_4\right]$ is:

Statement-$1$: The geometrical isomers of complex $\left[\mathrm{M}\right({\mathrm{NH}}_3{)}_4{\mathrm{Cl}}_2]$ are optically inactive

Statement-$2$: Both geometrical isomers of the complex $\left[\mathrm{M}\right({\mathrm{NH}}_3{)}_4{\mathrm{Cl}}_2]$ possess axis of symmetry.