The $\pi-$acid ligand which uses its $d-$orbital during synergic bonding in its complex compound is:

Which of the following complexes has the highest $C-O$ bond length?

The $\pi-$acid ligand which uses its $d-$orbital during synergic bonding in its complex compound.

When Ethane-$1,2$-diamine is added progressively to an aqueous solution of Nickel $(II)$ chloride,the sequence of colour change observed will be :

In an ammoniacal solution,copper ions form the complex ion $[Cu(NH_3)_4]^{2+}$,but this does not occur in an acidic solution. The reason for this is:

The purple color of $KMnO_4$ is due to which of the following?