Question

Boiling points of NH3 and HF are abnormally high as compared to those of hydrides of other elements in their respective groups,explain

Answer 1

For N HF molecules, there are 3N lone pairs and 1N H atoms, so at most N hydrogen bonds can form (even though an individual HF molecule can hydrogen bond to four other HF molecules). (c) HF and NH3 make fewer hydrogen bonds than H2O does, so H2O is expected to have a higher boiling point.