Order of first ionisation potentials of elements `Li,Be,B, Na` is

Options

A. LigtBegtBgtNa
B. BegtBgtLigtNa
C. BegtLigtBgtNa
D. BgtBegtLigtNa

Answer

B

Explanation

Na: `1s^(2)2s^(2)2p^(6) 3s^(1), Li : 1s^(2)2s^(2)`
`Be : 1s^(2) 2s^(2), B: 1s^(2)2s^(2)2p^(1)`
Thus correct order of `I.E_(1)` is as follows
Be gtBgtLigtNa
`IE_(1)` of Be is more than B. it is due to its extra stable electronic configuration with fully filled 2s-subshell