Which of the following statement(s) is/are correct for ${\mathrm{ClO}}_4^{-}$  oxoanion?

 

All $\mathrm{Cl}-\mathrm{O}$ bonds are identical and chlorine atom is ${\mathrm{sp}}^3$ hybridised

The chemical bonding takes place in ground state and charge dispersion is more than  ${\mathrm{ClO}}_3^{-}$ oxoanion.

It has total $4p\pi -d\pi$  bonds between chlorine and oxygen.

It does not have any tendency of polymerisation