Question

Which of the following statement is correct regarding bond angle of $P{H}_3$?

• A. Bond angle is much less than $N{H}_3$
• B. Bond angle is greater than $P{F}_3$
• C. Bond angle is slightly more than $N{H}_3$
• D. Bond angle is slightly less than $N{H}_3$

Answer 1

The correct option is A Bond angle is much less than $N{H}_3$


(a) $P{H}_3$ is a Drago's compound. It does not participate in hybridisation and percentage of $s$ character high with bond angle ${93}^0$ and $N{H}_3$ $P{H}_3$ is not a Drago's compound. It does participate in hybridisation with bond angle ${107}^0$. Bond angle of $P{H}_3$ is much less than $N{H}_3$ so option (c) and (d) incorrect.


(b) Between $P{H}_3$ and $P{F}_3$ the $P{F}_3$ has more bond angle. In $P{F}_3$ the lone pair on the phosphorus pushes the $P-F$ bonding electrons away from itself, and resulting in resonance, leading to partial double bond character. As result repulsions between $P–F$ bonds are large and hence the bond angle is large. So option (b) is incorrect