Assign suitable reason for the following: 1. BiH3 is the strongest reducing agent among all the hydrides of group 15 elements.

Question

Assign suitable reason for the following:

1. BiH₃ is the strongest reducing agent among all the hydrides of group 15 elements.
2. H₂O is a liquid but H₂S is a gas.
3. O₃ acts as a powerful oxidising agent.

Answer 1

1. Among 15th group elements, Bi is of the largest size and hence Bi-H bond is the longest.
   As a result BiH₃ acts as the strongest reducing agent because of easy formation of H₂.
2. Due to intermolecular hydrogen bonding, H₂O is a liquid whereas H₂S which does not have such bonds exist as a gas.
3. O₃ gets dissociated to give nascent oxygen which is responsible for its strong oxidising action
   O → O + ‘O’