In which of the following molecules, the number of lone pairs of electrons on central atom and the number of $d$-orbitals involved in the hybridisation of central atom, is same?

From the following, identify the ions with same bond order.

I. $\mathrm{CN}^{-} \quad$ II. $\quad \mathrm{N}_2^{+}$

III. $\mathrm{O}_2^{2-}$ IV. $\mathrm{NO}^{+}$

$$ \text { Match the following. } $$

The correct answer is

Which one of the following compounds is having maximum 'lone pair-lone pair' electron repulsions?