Identify the number of molecules in which the central atom has one lone pair of electrons from the following list $$ \mathrm{PbCl}_2, \mathrm{PH}_3, \mathrm{ClF}_3, \mathrm{SF}_4, \mathrm{BF}_3, \mathrm{SnCl}_2 $$

$\mathrm{sp}^2$ Hybridisation Trigonal planar geometry.
$\mathrm{sp}^3$ Hybridisation
$\mathrm{sp}^3 \mathrm{~d}$ Hybridisation Trigonal bipyramidal geometry T-shape.
$\mathrm{sp}^3 \mathrm{~d}$ Hybridisation Trigonal bipyramidal geometry see saw shape.
$\mathrm{sp}^2$ Hybridisation Trigonal planar geometry
$\mathrm{sp}^2$ Hybridisation Trigonal planar geometry So total 4 molecules has one lone pair of electrons on central atom.