Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R . Assertion A : PH 3 has lower boiling point than NH 3 . Reason R : In liquid state NH 3 molecules are associated through Vander Waal's forces, but PH 3 molecules are associated through hydrogen bonding. In the light of the above statements, choose the most appropriate answer from the options given below:

Step-by-step solution

The molecular formulas for ammonia and phosphine are NH 3 and PH 3 , respectively. As we know, Nitrogen is more electronegative and smaller in size than phosphorus. Therefore, hydrogen bonding occurs in ammonia in comparison to phosphine. Hydrogen bonding is the force of attraction between hydrogen and an electronegative element which is smaller in size. In the case of phosphine, only weak van der waal’s forces of attraction exist between the molecules. Since hydrogen bonding is stronger than weak van der waal’s fo