In how many of the following molecules is the central atom surrounded by atleast $10$ electrons?

(i) ${\mathrm{ClO}}_2$ (ii) ${\mathrm{NO}}_3^{-}$ (iii) ${\mathrm{O}}_3$ (iv) ${\mathrm{PCl}}_5$ (v) ${\mathrm{SO}}_3$ (vi) ${\mathrm{SO}}_4^{2-}$ (vii) ${\mathrm{CO}}_2$ (viii) ${\mathrm{N}}_3^{-}$ (ix) ${\mathrm{I}}_3^{-}$

Number of molecule or ions having lone pairs $\ge 2$ for the central atom are:

(i) ${\mathrm{HClO}}_4$ (ii) ${\mathrm{HClO}}_3$ (iii) ${\mathrm{HClO}}_2$ (iv) ${\mathrm{H}}_2\mathrm{O}$ (v) ${\mathrm{NH}}_2^{-1}$ (vi) ${\mathrm{CIF}}_3$ (vii) ${\mathrm{XeF}}_2$ (viii) ${\mathrm{XeF}}_4$ (ix) ${\mathrm{XeF}}_6$ (x) ${\mathrm{I}}_3^{-1}$ (xi) ${\mathrm{N}}_3^{-1}$ (xii) ${\mathrm{O}}_3$ (xiii) ${\mathrm{ICl}}_4^{-}$ (xiv) ${\mathrm{ICl}}_2^{+}$ (xv) ${\mathrm{XeO}}_3$ (xvi) ${\mathrm{XeF}}_5^{-1}$

Find the number of molecules having two lone pairs on the central atom.

(i) ${\mathrm{I}}_3^{+}$ (ii) ${\mathrm{XeF}}_2$ (iii) ${\mathrm{XeF}}_4$ (iv) ${\mathrm{H}}_2\mathrm{O}$ (v) ${{\mathrm{NH}}_2}^{-}$ (vi) ${\mathrm{H}}_2\mathrm{S}$ (vii) ${\mathrm{H}}_2{\mathrm{SO}}_4$ (Viii) ${\mathrm{NF}}_3$

Consider $\mathrm{y}$-axis as internuclear axis. How many of the following will lead to $\mathrm{\pi }$ bond formation:

(i) ${\mathrm{p}}_{\mathrm{y}}-{\mathrm{p}}_{\mathrm{y}}$ (ii) ${\mathrm{p}}_{\mathrm{x}}-{\mathrm{p}}_{\mathrm{x}}$ (iii) ${\mathrm{p}}_{\mathrm{z}}-{\mathrm{p}}_{\mathrm{z}}$ (iv) ${\mathrm{d}}_{\mathrm{xy}}-{\mathrm{d}}_{\mathrm{xy}}$ (v) ${\mathrm{d}}_{\mathrm{yz}}-{\mathrm{d}}_{\mathrm{yz}}$ (vi) ${\mathrm{p}}_{\mathrm{x}}-{\mathrm{d}}_{\mathrm{xy}}$ (vii) ${\mathrm{d}}_{\mathrm{xy}}-{\mathrm{p}}_{\mathrm{z}}$ (viii) ${\mathrm{d}}_{\mathrm{xz}}-{\mathrm{d}}_{\mathrm{xz}}$