Please,trying to understand boiling point, mass, intermolecular force affecting the ranking of H2Se, H2S, H2Te

Answer 1

vdW forces rise as you go down Group 6 (16). This correlates quite well with the size and Mr of the molecules, and the size of their molecular electron clouds.
It is H2O which is the odd one out in this group, having an MP and BP far higher than predicted from the others in the sequence - entirely due to hydrogen bonding.

Answer 2

same shape, bent due to the 2 lone pair of electrons on top of O and S bp of H2S << H2O due to the lack of hydrogen bonding in H2S H2S, london dispersion forces present vs hydrogen bonding in H2O S is a larger atom than O O is more electronegative than S