Do have nonmetals have high melting points?

Yes non metals do have high melting and boiling points. This is because they have strong intemolecular forces that are hard to overcome.

A2. Their melting points vary. Obviously gases such as nitrogen and oxygen have low melting points, but Silicon (1414oC) and Diamond ( around 1700oC) are rather high. Phosphorous and Sulfur on the other hand are rather low.