JEE Main · 2026 · 21 Jan 2026 · Shift 1 · Classification of Elements and Periodicity

First ionization energy rises across a period and falls down a group, and the half-filled 3p${}^3$ of phosphorus raises it above sulphur, giving F $>$ P $>$ S $>$ B, so trend A is correct. Electron affinity is greatest for group 17, and within it chlorine exceeds fluorine because of the small, electron-crowded 2p shell of F, giving Cl $>$ F $>$ S $>$ P, so trend B is correct. Metallic character should read K $>$ Mg $>$ Al $>$ B, so the quoted K $>$ Al $>$ Mg $>$ B is wrong and trend C fails. Basic character of the oxides falls across a period and rises down a group, giving K${}_2$O $>$ Na${}_2$O $>$ MgO $>$ Al${}_2$O${}_3$, so trend D is correct. The correct trends are A, B and D only.