Which of following species are hypervalent?

(P) ${\mathrm{ClO}}_4^{-}$

(Q) ${\mathrm{BF}}_3$

(R) ${\mathrm{SO}}_4^{2-}$

(S) ${\mathrm{CO}}_3^{2-}$

A molecule that has one or more main group elements with more than eight electrons in their valence shells is said to be hypervalent. 

As a result, ${\mathrm{ClO}}_4^{-}$ is hypervalent because it has more than 8 electrons, while ${\mathrm{SO}}_4^{2-}$ is hypervalent because it has more than 8 electrons.