If the ionization enthalpy and electron gain enthalpy of an element are 275 and 86 kcal mol-1 respec — Periodic Table and Periodicity Chemistry Question

💡 Solution & Explanation

Step 1: In the first transition series (3d), atomic radius decreases from Scandium (Sc) to Chromium (Cr) because the increase in nuclear charge outweighs the shielding of the d-electrons. Step 2: For option (b), atomic size does not decrease continuously up to Zn; repulsions between d-electrons cause Cu and Zn to be larger than Ni. For option (c), N^3- is larger than O^2-, so the order is incorrect. Step 3: Therefore, the only correct order is Sc > Ti > V > Cr, which corresponds to option (a).