Question

What is the Significance of boiling point or melting point of a substance?

Answer 1

Melting points are important because they indicate compound purity. If you synthesize a compound and measure its melting point and the melting point is well-defined (i.e., the compounds melts over a very small temperature range) and the temperature agrees with values reported in the literature (if those are available), then it is a strong piece of evidence that the sample is relatively pure. Boiling points are important for the same reason, a well-defined boiling point indicates purity. 

Answer 2

boiling point and melting point indicate the force of attraction between the particles of matter.if boiling point is higher, the force of attraction is also higher.the same is for melting point