Question

Assertion: The first ionization energy of aluminium is lower than that of magnesium.
Reason: The ionic radius of aluminium is smaller than that of magnesium.

• A. If both Assertion and Reason are true and the Reason is a correct explanation of the Assertion
• B. If both Assertion and Reason are true but Reason is not a correct explanation of the Assertion
• C. If Assertion is true but the Reason is false
• D. If both Assertion and Reason are false

Answer 1

Answer: (A)

The elements of group $III$ have $ns ^{2} \,n p^{1}$, configuration. Since $p$ -electrons are held less tightly than $s-$ electrons. The first $I E$ of each element is low as compared to the first $IE$ of alkaline earth metal.