Number of compounds from the following with zero dipole moment is _________.

$$\mathrm{HF}, \mathrm{H}_2, \mathrm{H}_2 \mathrm{~S}, \mathrm{CO}_2, \mathrm{NH}_3, \mathrm{BF}_3, \mathrm{CH}_4, \mathrm{CHCl}_3, \mathrm{SiF}_4, \mathrm{H}_2 \mathrm{O}, \mathrm{BeF}_2$$

In the lewis dot structure for $$\mathrm{NO}_2^{-}$$, total number of valence electrons around nitrogen is _________.

Number of compounds / species from the following with non-zero dipole moment is _________.

$$\mathrm{BeCl}_2, \mathrm{BCl}_3, \mathrm{NF}_3, \mathrm{XeF}_4, \mathrm{CCl}_4, \mathrm{H}_2 \mathrm{O}, \mathrm{H}_2 \mathrm{~S}, \mathrm{HBr}, \mathrm{CO}_2, \mathrm{H}_2, \mathrm{HCl}$$

Number of molecules/species from the following having one unpaired electron is ________.

$$\mathrm{O}_2, \mathrm{O}_2^{-1}, \mathrm{NO}, \mathrm{CN}^{-1}, \mathrm{O}_2^{2-}$$