Question

The first ionisation potential of `Na,Mg,Al` and `Si` are in the order
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 1

Correct Answer - A
Ionisation energy increases from left to right in a period.
However, exception occur between group 2 and group 13 elements on account of stability of electronic configuration of valence shell.

`implies` The desired order is `Na lt Mg gt AI lt Si`