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

The number of lone pairs of electrons on the central atom of $\mathrm{XeO}_3, \mathrm{XeOF}_4$ and $\mathrm{XeF}_6$ respectively is

In which of the following options, the molecules are correctly arranged in the increasing order of their bond angles?

In which of the following the compounds are correctly arranged in the decreasing order of boiling points?