Given below are two statements:
Statement I: The correct order in terms of atomic/ionic radii is $$Al >Mg > Mg^{2+} >Al^{3+}$$
Statement II: The correct order in terms of the magnitude of electron gain enthalpy is Cl > Br >S >O.
In the light of the above statements, choose the correct answer from the options given below:

• Statement I: The given order is $$Al > Mg > Mg^{2+} > Al^{3+}$$.
  • Atomic Radii: Across period 3, atomic size decreases as effective nuclear charge increases ($$Mg > Al$$).
  • Ionic Radii: For isoelectronic species ($$Mg^{2+}$$ and $$Al^{3+}$$, both having 10 electrons), a higher nuclear charge draws electrons closer, making $$Mg^{2+} > Al^{3+}$$.
  • Thus, the correct combined order is $$Mg > Al > Mg^{2+} > Al^{3+}$$. (Statement I is False)
• Statement II: The given order of negative electron gain enthalpy magnitude is $$Cl > Br > S > O$$.
  • Halogens ($$Cl, Br$$) release more energy than chalcogens ($$S, O$$) upon electron addition.
  • Within Group 17, $$Cl$$ is greater than $$Br$$ ($$Cl > Br$$).
  • Within Group 16, due to the exceptionally small size and inter-electronic repulsion of oxygen, sulfur has a higher magnitude than oxygen ($$S > O$$).
  • Thus, the overall magnitude trend is $$Cl > Br > S > O$$. (Statement II is True)

Conclusion:

Statement I is false because magnesium atoms are larger than aluminum atoms, whereas Statement II correctly outlines the electron gain enthalpy magnitudes.

Answer: Option A — Statement I is false but Statement II is true