The melting point of O₂(s) is -218^oC. Would you expect the melting point of N₂(s) to be -210^oC, -218^oC, or 226^oC? Explain your answer.

Identify the two most important intermolecular forces that cause each of the following to crystallize:

i. CH₃CH₂OH
ii. CH₃CH₂Cl
iii. NH₄F, an ionic solid