Why all bonds of PCl5 are not same

In PCl5 Phosphorous is a central atom and the ground state electronic configuration

As Principal quantum number (n) of valance shell is equal to 3 thus allowed values of azimuthal quantum number (l) are 0,1 2 this can be interpreted as s-orbital, p-orbital and d-orbital. The d-orbital is not filled as per aufbau rule 

d-orbital is empty so thus exited state electronic configuration of phosphorous can be written as

the orbital used in the hybridisation are

and the shape of the molecule is trigonal bi-pyramidal  

   

There are three equatorial chlorine atoms and two axial chlorine atoms.

There are lone pair of electrons on the chlorine atoms,  So chlorine atoms repel there  adjacent atoms. The repulsion on equatorial atoms is cancelled off but repulsions on axial chlorine atoms is considerable and doesn't get cancelled off thus bond length of axial chlorine atoms is more than equatorial chlorine atoms