In the coordination complex $[E(en)_2(C_2O_4)]NO_2$,the coordination number and oxidation state of $E$ are respectively:

$A$ complex compound of $Co^{3+}$ with molecular formula $CoCl_{x} \cdot yNH_3$ gives a total of $3$ ions when dissolved in water. How many $Cl^{-}$ ions satisfy both primary and secondary valencies in this complex?

What is the primary and secondary valency of the central metal in the complex $[Co(C_2O_4)_2(H_2O)_2]^{-}$?

How many $EDTA$ molecules are required to form an octahedral complex with a $Ca^{2+}$ ion?

Which of the following compounds is a zero-valent metal complex?

The correct order of the stoichiometries of $AgCl$ formed when $AgNO_3$ in excess is treated with the complexes $CoCl_3 \cdot 6NH_3$,$CoCl_3 \cdot 5NH_3$,and $CoCl_3 \cdot 4NH_3$ respectively is: