Arrange the species in each group in order of increasing ionisation energy and give reason:
a. `K^(o+)`,`Cl^(ө)`,`Ar` , b. `Na`,`Mg`,`Al` , c. `C`,`N`,`O`

Explanation

a. `K^(o+)gtArgtCl^(ө)`, because nuclear charge goes on decreasing .
b. `NaltAlltMg`, because `Mg` has stable electronic configuration where `Na` is larger atomic size due to which it has lowest ionisation energy.
c. `CltOltN`, because `N` has half-filled `p`-orbital which is more stable whereas carbon is larger in size.