Which of these molecules have non-bonding electron pairs on the cental atom? $\mathrm{I}: \mathrm{SF}_4 : \mathrm{II}: \mathrm{ICl}_3 : \mathrm{III}: \mathrm{SO}_2$

For $\mathrm{SF}_4$, the central atom is sulfur (group 16). Sulfur has 6 valence electrons. It forms 4 bonds with fluorine atoms, leaving $6 - 4 = 2$ electrons, which corresponds to 1 lone pair on the sulfur atom.

For $\mathrm{ICl}_3$, the central atom is iodine (group 17). Iodine has 7 valence electrons. It forms 3 bonds with chlorine atoms, leaving $7 - 3 = 4$ electrons, which corresponds to 2 lone pairs on the iodine atom.

For $\mathrm{SO}_2$, the central atom is sulfur (group 16). Sulfur has 6 valence electrons. It forms 2 double bonds with oxygen atoms (total 4 electrons used for bonding), leaving $6 - 4 = 2$ electrons, which corresponds to 1 lone pair on the sulfur atom.

Since all three molecules $\mathrm{SF}_4$, $\mathrm{ICl}_3$, and $\mathrm{SO}_2$ possess non-bonding electron pairs on their respective central atoms, the correct option is I, II and III.

Answer: I, II and III