The first ionisation enthalpy of Na, Mg and Si are 496, 731 ,776 kJ/mol respectively.

Question

The first ionisation enthalpy of Na, Mg and Si are 496, 737 ,776 kJ/mol respectively. What will be the first ionisation enthalpy potential of Al in kJ/mol?

(a) > 766 kJ/mol

(b) > 496 and < 737 kJ

(c) >737 and < 766 kJ/mol

(d) > 496 kJ/mol

Answer 1

Correct option  (b) > 496 and < 737 kJ

Explanation:

The ionisation enthalpy of Al is lower than that of Mg as 3p¹ electron of Al is easier to remove than to remove an electron from fully-filled 3s-orbital of Mg.