How would you explain that the first ionisation energy of Na is lawer than that of Mg but is second inoisation enthalpy is higher than that of Mg ?

Explanation

First ionisation enthalpy of Na is lawer than that of Mg because the nuclear charge is lesser for Na than Mg. in the second ionisation energy for Na an electron is to be removed from N `a^+` which requires large energy than the removel of s electron from M `g^+` because `Na^+(1s^2 2s^2 2p^6)` has mare table electronic configuration than `Mg^+ (1s^2 2s^2 2p^6 3s^1)`.