$H_2N - CH_2 - CH_2 - NH_2$ acts as a:

What type of ligand is $EDTA$?

The $NO$ molecule,

What is the number of electrons lost by $Cr$ in a complex $[Cr(CO)_6]$?

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

Potassium cyanide is made alkaline with $NaOH$ and boiled with thiosulphate ions. The solution is cooled and acidified with $HCl$ and this solution with iron $(III)$ chloride produces :-