The number of non-polar molecules from the following is _________. $$\mathrm{HF}, \mathrm{H}_2 \mathrm{O}, \mathrm{SO}_2, \mathrm{H}_2, \mathrm{CO}_2, \mathrm{CH}_4, \mathrm{NH}_3, \mathrm{HCl}, \mathrm{CHCl}_3, \mathrm{BF}_3$$

Sum of bond order of CO and NO$$^+$$ is ________.

The maximum number of lone pairs of electrons on the central atom from the following species is ____________.

$$\mathrm{ClO}_{3}{ }^{-}, \mathrm{XeF}_{4}, \mathrm{SF}_{4}$$ and $$\mathrm{I}_{3}{ }^{-}$$

The number of molecules from the following which contain only two lone pair of electrons is ________

$$\mathrm{H}_{2} \mathrm{O}, \mathrm{N}_{2}, \mathrm{CO}, \mathrm{XeF}_{4}, \mathrm{NH}_{3}, \mathrm{NO}, \mathrm{CO}_{2}, \mathrm{~F}_{2}$$