Question

Bond angles in $N{H}_3$ and $H_{2}O$ are :

• A. ${109}^{\circ }$ and ${103}^{\circ }$
• B. ${107}^{\circ }$ and ${104.5}^{\circ }$
• C. ${102}^{\circ }$ and ${104}^{\circ }$
• D. ${109}^{\circ }$ and ${90}^{\circ }$

Answer 1

The correct option is B ${107}^{\circ }$ and ${104.5}^{\circ }$

$\begin{array}{c}\text{Both}{NH}_3\text{and}{H}_{2}O\text{are}{sp}^3\text{hybridised, so the bond}\text{angle should be}{109.5}^{\circ }\text{.}\\ \text{But}{NH}_3\text{has one lone pair and water has two lones pairs.}\end{array}$

$\begin{array}{c}\text{So, the bond angle in}N{H}_3\text{is less than}{109.5}^{\circ }\text{which}is\\ \text{about}{107}^{\circ }\text{.}\text{As water has two lone pairs the bond angle is further}\\ \text{reduced to}{104.5}^{\circ }\text{Bond angles in}{NH}_3\text{and}{H}_{2}O\text{are}{107}^{\circ }\text{and}{104.5}^{\circ }\end{array}$