Question

Question 04

Hydrogen bonds are formed in many compounds e.g., $H_{2}O,HF,N{H}_3$. The boiling point of such compounds depends to a extent on the strength of hydrogen bond and the number of hydrogen bonds. The correct decreasing order of the boiling points above compounds is

(a) $HF>H_{2}O>N{H}_3$

(b) $H_{2}O>HF>N{H}_3$

(c) $N{H}_3>HF>H_{2}O$

(d) $N{H}_3>H_{2}O>HF$

Answer 1

Answer: (b) $H_{2}O>HF>N{H}_3$

The strength of H-bond is in the order H...F > H....O > H.....N.

But each $H_{2}O$ molecule is linked to four other $H_{2}O$ molecules through H-bonds whereas each HF molecule is linked only to two other HF molecules.

Hence, boiling point of $H_{2}O$ > b.p of HF > b.p. of $N{H}_3$