Question

Which hydride is most stable?

Options

• AsH₃

• SbH₃

• N₂O₄

• NH₃

Answer 1

NH₃

Explanation:

The thermal stability of group 15 hydrides decreases down the group due to increasing bond length and decreasing bond energy. NH₃ has the shortest N-H bond and the highest bond energy, making it the most stable. SbH₃ is the least stable due to its long and weak \[\ce{Sb - H}\] bond. Hence, the order of stability is NH₃ > PH₃ > SbH₃.