Question

Among NH₃, PH₃, AsH₃, SbH₃ and BiH₃, which does possess the highest reducing power and why?

Answer 1

1. Among NH₃, PH₃, AsH₃, SbH₃, and BiH₃, the hydride with the highest reducing power is BiH₃.
2. Reducing power increases down the group from NH₃ to BiH₃.
3. This is because thermal stability decreases down the group, making BiH₃ more prone to give off hydrogen.
4. The \[\ce{M - H}\] bond length increases down the group, lowering bond energy and stability.

Hence, BiH₃ acts as the strongest reducing agent, while NH₃ is the least reducing among them.