The first ionisation energies in eV/atom of magnesium and aluminium are respectively given by which of the following?

Options

A. 7.64, 5.98
B. 7.64, 7.64
C. 5.98, 7.64
D. 5.98, 5.98

Answer

A

Explanation

IE of Mg `gt` IE of Al
`Mg: 1s^2, 2s^2 2p^6, 3s^2`
`Al : 1s^2, 2s^2 2p^ 6, 3s^2 3p^1`
The first electron remove from Mg is more difficult because it has fulfilled orbital configuration while Al has partial filled orbital configuration.