Chemical Bonding And Molecular Structure

The sets of molecules in which central atom has no lone pair of electrons are

I. $\mathrm{SnCl}_2, \mathrm{NH}_3, \mathrm{SF}_4$

II. $\mathrm{HgCl}_2, \mathrm{SO}_3, \mathrm{SF}_6$

III. $\mathrm{BeCl}_2 \mathrm{BF}_3, \mathrm{PCl}_5$

IV. $\mathrm{ClF}_3, \mathrm{BrF}_5, \mathrm{XeF}_6$