Which orbital is non directional?
They are non directional because they are spherical in shape and probability of finding electrons at a particular distance from the nucleus is same in all directions.
Ammonia has higher boiling point than phosphine. Give reason.
It is due to inter-molecular hydrogen bond.
Nitrogen present in ammonia is capable of forming hydrogen bonding with neighboring ammonia molecules which increases their intermolecular force of attraction. As a result, higher amount of heat energy needs to be supplied to break this bond. So, it has a higher boiling point.
However, hydrogen bonding cannot be imagined in Phosphine.