What is the number of $N$ atoms present in $EDTA$?

According to Werner's theory,the primary valency of a central metal ion is:

If $1/3$ of the total chlorine in the compound $CrCl_3 \cdot 6H_2O$ is precipitated by adding $AgNO_3$ to its aqueous solution,what is the possible structure of the compound?

The complex of $Ni^{2+}$ ion and dimethylglyoxime contains $..........$ number of Hydrogen $(H)$ atoms.

In potassium trioxalatoaluminate $(III)$, what are the primary and secondary valency of the central atom respectively?

The coordination number of $Th$ in $K_4[Th(C_2O_4)_4(OH_2)_2]$ is
$(C_2O_4^{2-} = \text{Oxalato})$