Question

Which of the following has higher polarising power- ${\mathrm{Al}}^{3+}$ ,${\mathrm{Mg}}^{+2}$ ,${\mathrm{O}}^{2-}$?

Answer 1

1. Polarising power is defined as the extent to which a cation can polarise a given anion.
2. Polarising power is directly proportional to charge density, i.e. charge to radius ratio.

So, from the given ions, we can conclude ${\mathrm{Al}}^{3+}$has the highest polarising power as it has a charge of +3.