Which of the following species have undistorted octahedral structures?

(P) ${\mathrm{SF}}_6$ (Q) ${\mathrm{PF}}_6^{-}$ (R) ${\mathrm{SiF}}_6^{2-}$(S) ${\mathrm{XeF}}_6$

Select the correct answer using the codes given below:

XeF6​ has a distorted octahedral structure due to the presence of one lone pair of electrons on the Xe atom. PF6−​ and SiF62−​ have undistorted octahedral structures. 

P, Q, R have perfect octahedral shape. So, correct code is Q and R.