Question

What is the trend of boiling points of hydrides of N, O, and F?

• A. Due to lower molecular masses $N{H}_3,H_{2}O$ and HF have lower boiling points than those of the subsequent group member hydrides
• B. Due to higher electronegativity of N, O and F; $N{H}_3,H_{2}O$ and HF show hydrogen bonding and hence higher boiling points than the hydrides of their subsequent group members.
• C. There is no regular trend in the boiling points of hydrides
• D. Due to higher oxidation states of N, O and F, the boiling points of $N{H}_3,H_{2}O$ and HF are higher than the hydrides of their subsequent group members.

Answer 1

Answer: (B)

Due to higher electronegativity of N, O and F; $N{H}_3,H_{2}O$ and HF show hydrogen bonding and hence higher boiling points than the hydrides of their subsequent group members.

The boiling point increases with increase in molecular masses. But in the case of $N,O$ and $F$ they show the higher boiling point in molecules.

This is due to the higher electronegativity of $N,O$ and $F$ which leads to hydrogen bonding in $N{H}_3,H_{2}O$ and $HF$ due to which the boiling point of these increases & is higher than the hydrides of their subsequent group members.