Which of the following dissolves in ionic solvents?

Which of the following is the most polar?

Which has maximum dipole moment?

$BF_3$ and $NF_3$ both are covalent compounds but $NF_3$ is polar whereas $BF_3$ is non-polar. This is because

The geometry and dipole moment of $H_2S$ respectively are

The dipole-dipole interaction energy between polar molecules in the solid state will be proportional to ...... [if $r$ denotes the distance between polar molecules]