The decreasing order of thermal stability of hydrides of group 15 elements is
The decreasing order of thermal stability of hydrides of group 15 elements is

 

 

 

Solution: The correct option is 2.

Hydride stability reduces as one moves along the group from NH3 to SbH3. This is because their bond dissociation enthalpy has decreased. The ease with which hydrogen can be lost is strongly related to reducing character. SbH3 has the strongest reducing property of all the hydrides in group 15, while NH3 is a light reducing agent.