The IUPAC name of $\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_4 \mathrm{Cl}\left(\mathrm{NO}_2\right)\right] \mathrm{Cl}$ is

Square planar complex of the type $M_{\text {AXBL }}$ (where $A, B, X$ and $L$ ) are unidenate ligands shows following set of isomers

The coordination number and the oxidation state of the. element ' $M$ ' in the complex $\left[\mathrm{M}(e n)_2\left(\mathrm{C}_2 \mathrm{O}_4\right)\right] \mathrm{NO}_2$ {where (en) is ethan1, 2-diamine) are respectively

According to crystal field theory, the $M-L$ bond in a complex is