Which one of the following elements is unable to form $M F_{6}^{3-}$ ion?\

Question

Professor PC Thomas Classes · Answer

(c) : Boron does not have vacant $d$-orbitals in its valence shell, so it cannot expand its covalency beyond 4 i.e., ' $B$ ' cannot form the ions like $M \mathrm{~F}_{6}^{3-}$.