What is the relationship between the molar mass of Ne, Ar, Kr, and Xe and the melting points of their solids?

Answer 1

The general rule is that melting point increases as the molar mass increases.
Here is a table that list the melting points (other properties, also) for all of the noble gases.
http://en.wikipedia.org/wiki/Noble_gas#Physical_and_atomic_properties

Answer 2

Thanks! But, does this rule apply to any molecular compounds. I noticed that for H2O, H2S, H2Se H2Te, the rule applies to H2S to H2Te but is different for H2O. Why is that??

Answer 3

Because of hydrogen bonding. If you will note, the boiling point decreases from H2Te to H2Se to H2S but the electronegativity of O is large enough that H bonding takes a much larger effect. As a result the boiling point for H2O is much higher than we would expect it to be.(We might expect it to be a gas.) Does this happen with other groups? You bet it does and for the same reason. N, O, and F are the main ones that we have H bonding. Look at the boiling points of SbH3, AsH3, PH3, and NH3. The latter is way off target. Same thing with HI, HBr, HCl, HF.