With which of the following configuration the lowest value of first IE is associated

Options

A. `1s^(2)2s^(2)2p^(6)3s^(2)`
B. `1s^(2)2s^(2) 2p^(5)`
C. `1s^(2)2s^(2)2p^(6)`
D. `1s^(2)2s^(2)2p^(6)3s^(2)3p^(3)`

Answer

A

Explanation

The 3s electron in A will be loosely held due to large size of atoms