Question

The correct order of energy of 2s orbitals in H, Li, Na and K, is

• A. K < Na < Li < H
• B. Na < Li < K < H
• C. Na < K < H < Li
• D. H < Na < Li < K

Answer 1

The correct option is A K < Na < Li < H

As we go down the group $IA$, there is increase in the number of shells so size of atom increases and energy of 2s orbital decreases.