Question

Assertion :$M{g}^{2+}$ and $A{l}^{3+}$ are isoelectronic but ionic radius of $A{l}^{3+}$ is less than that of $M{g}^{2+}$. Reason: The effective nuclear cahrge on the outershell electrons in $A{l}^{3+}$ is more than that in $M{g}^{2+}$.

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
• B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
• C. Assertion is correct but Reason is incorrect
• D. Both Assertion and Reason are incorrect

Answer 1

The correct option is A Both Assertion and Reason are correct and Reason is the correct explanation for Assertion

In case of isoelectronic species, effective nuclear charge increases with increase in atomic number Z (with increase in protons). This results in decrease in size and hence, ionic radius of $A{l}^{3+}$ < $M{g}^{2+}$

Hence , we can say Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.