Hello!

Take a look at the Lewis structure of PCl5.

In order for a molecule made of more than 2 atoms to be polar, one of the following must be true.

1. There must be at least one lone (unshared) pair of electrons located on the central atom, or
2. The outer atoms must not all be from the same element.

Neither of those statements is true of PCl5; hence, it is nonpolar.

Hope this helps!

Hello,

When we give reason about nonequivalent bonds in PCl5 we say that it is based on the evidence that when we heat PCl5 then cl2 gas is released and PCl3 remains,which suggest that Equatorial bonds are stronger then axial bonds.

So with this discussion we can conclude that

Two axial bond are identical

Three equatorial bond are identical

Pcl5 has trigonal bipyramidal structure.

the trigonal bipyramidal structure makes the arrangement as that opposite bonds cancel the dipole moment of each other hence the PCl5 is nonpolar.