Question

Assertion $Na^{+}$ and $Al^{3+}$are isoelectronic but the magnitude of ionic radius of $Al^{3+}$ is less than that of $Na^{+}$.
Reason The magnitude of effective nuclear charge of the outer shell electrons in $Al^{3+}$ is greater than that in $Na^{+}$.

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

Answer 1

Answer: (A)

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 Hence. ionic radius of $Al ^{3+} < Na ^{+}$