Question

Correct order of polarising power is
(a) Cs⁺ < K⁺ < Mg²⁺ < Al³⁺(b) K⁺ < Cs⁺ < Mg²⁺ < Al³⁺
(c) Cs⁺ < K⁺ < Al³⁺ < Mg²⁺ (d) K⁺ < Cs⁺ < Al³⁺ < Mg²⁺

Answer 1

The correct order of polarising power among Cs⁺ ,K⁺ ,Mg²⁺ , Al³⁺ is

1) we know polarising power is the ability id a cation to distort an anuon also we know that polarising Power is inversely proportional to size of cation

2) Below is the order of size in increasing order

Al³⁺ < Mg²⁺ < K⁺ < Cs⁺

so the order of polarising power is its reverse order so

Cs⁺ <K⁺ <Mg²⁺ <Al³⁺

3) So option (a) is the correct answer

Answer 2

Correct order of the polarising power would be-

Cs+ < K+ < Mg²+ < Al³+

1) Polarising power of an ion is it's ability to distort the electron cloud.

2) Larger the size of the ion, greater is it's polarising power.

3) As we go down the periodic table, the ionic size decreases.

4) Whereas, as we go across the periodic table, the ionic size increases.

5) In the above mentioned ions, Cs+ and K+ is present in Group 1. Mg²+ is present in Group 2 and Al³+ is present in Group 13.

6) Following the periodic trend, the decreasing order of the ionic sizes would be-

Al³+ > Mg²+ > K+ > Cs+

This implies, their polarising power order would be-

Cs+ < K+ < Mg²+ < Al³+

Hence the correct option is (a)