Question

In which one of the following pairs the interatomic bond angle is ${109}^{\circ }{28}^{\prime }$, ${120}^{\circ }$ respectively :

• A. $N{H}_4^{+},B{F}_3$
• B. $N{H}_3,B{F}_4^{-}$
• C. $N{H}_2^{-},B{F}_3$
• D. None of the above

Answer 1

The correct option is A $N{H}_4^{+},B{F}_3$

a) $N{H}_4^{+}$ has interatomic bond angle of ${109}^{\circ }{28}^{\prime }$ and $s{p}^3$ hybridization but $B{F}_3$is $s{p}^2$ hybridized with ${120}^o$ bond angle.


b)$N{H}_3$ has bond angle of ${107}^o$ $s{p}^3$ hybridization but bond angle is less than ${109}^{\circ }{28}^{\prime }$ due to lone- pair - bond pair repulsion but $B{F}_4^{-}$ has a bond angle of ${109}^{\circ }{50}^{\prime }$


c)$B{F}_3$ is $s{p}^2$ hybridized with ${120}^o$ bond angle. and $N{H}_2^{-}$ has a bond angle of ${112}^o$ due to large amount of (lone- pair - bond - pair) repulsions