Question

In which of the following molecules, the bond lengths around the central atoms are not equal?

• A. $S{F}_6$
• B. $P{F}_5$
• C. $PC{l}_3$
• D. $B{F}_3$

Answer 1

The correct option is B $P{F}_5$

$S{F}_6$ has $s{p}^3{d}^2$ hybridisation, $B{F}_3$ has $s{p}^2$ hybridisation. In all of these , the bond lengths are equal. However, $P{F}_5$ has $s{p}^{3}d$ hybridization i.e. trigonal bi-pyramidal structure. In the triagonal plane, the bond angle is ${120}^{\circ }$ whereas the angle between the pyramidal bond and the plane is ${90}^{\circ }$

From the figure, we can say that it experiences different $bp-bp$ repulsion , due to which all the bond lengths are not equal.