The co-ordination number and the oxidation state of the element ‘M’ in the complex [M(en)₂(C₂O₄)] NO₂ {where (en) is ethan-1, 2-diamine} are respectively

The coordination number of M in [M(en)₂(C₂O₄)]NO₂ is 6 because en and C₂O₄ are bidentate ligands. Oxidation state of en is zero, C₂O₄ is -2 and NO₂ is -1.

Oxidation state of M (x) is calculated as:

$$\begin{gathered} \mathrm{x}+2\left(0\right)+-2+-1=0 \\ \mathrm{x}=+3 \end{gathered}$$