What are the forces of attraction between the following molecules?

Question

H2
NH3
H2O
HCL
CH4
C2H6

and why?

thanks

Answer 1

1st, 5th and 6th - vdW forces only, since they're non-polar.
HCl - dipole-dipole, because it's polar.
2nd and 3rd - H-bonding, because they're polar, have H, have at least one lone pair and have a Period 2 non-metal in.