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 :
C. Statement I is false but Statement II is true
Analyzing Statement I: The order given is Al > Mg > Mg²⁺ > Al³⁺. However, the correct atomic radii order should be Mg > Al because Mg is in group 2 (period 3) while Al is in group 13 (period 3), and moving right across a period decreases radius. The correct order would be Mg > Al > Mg²⁺ > Al³⁺. Therefore, Statement I is FALSE. Analyzing Statement II: Electron gain enthalpy magnitudes follow: Cl (highest, ~349 kJ/mol) > Br (~325) > S (~200) > O (~141). This is because Cl has the highest tendency to gain an electron due to its position and electronic configuration. Statement II is TRUE. Since Statement I is false and Statement II is true, the answer is option (3).
Related: Chemistry — Classification of Elements and Periodicity in Properties · All PYQ Banks