The first ionisation potential of `Na,Mg,Al` and `Si` are in the order

Options

A. Na lt Mg gt Al lt Si
B. Na gt Mg gt Al gt Si
C. Na lt Mg lt Al gt Si
D. Na gt Mg gt Al lt Si

Answer

A

Explanation

Ionisation energy increases from left to right in a period. However exception occurs in cases where ionisation would disrupt the stable half-filled or fully filled subshells. Ionisation energy of group 2 > Ionisation energy of group 13