Which of the following is a negative ligand?

Identify the homoleptic complex from the following:

In dichlorodioxalatochromium$(III)$,the primary and secondary valencies are respectively ......

The complex hexamineplatinum$(IV)$ chloride will give how many ions upon ionization?

The bonds in $K_4[Fe(CN)_6]$ are:

When $1 \ mol$ of the complex $Co(NH_3)_5Cl_3$ is dissolved in water,it yields $3 \ mol$ of ions. When $1 \ mol$ of the same complex reacts with $2 \ mol$ of $AgNO_3$,it produces $2 \ mol$ of $AgCl_{(s)}$. What is the structure of this complex?