JEE Main · 2026 · 04 Apr 2026 · Shift 1 · d and f Block Elements

Potassium dichromate is a strong oxidant in acidic medium and oxidises $\mathrm{Fe}{}^{2+}$ to $\mathrm{Fe}{}^{3+}$, turning $\mathrm{FeSO}{}_4$ into $\mathrm{Fe}{}_2(\mathrm{SO}{}_4){}_3$, so statement (A) is correct. Sodium dichromate is deliquescent and cannot act as a primary standard, the role taken instead by potassium dichromate, so statement (B) is false. Chromate and dichromate interconvert with pH, $2\mathrm{CrO}{}_4{}^{2-}+2\mathrm{H}{}^{+}\rightleftharpoons \mathrm{Cr}{}_2\mathrm{O}{}_7{}^{2-}+\mathrm{H}{}_2\mathrm{O}$, so statement (C) is correct. The bridging $\mathrm{Cr}-\mathrm{O}-\mathrm{Cr}$ angle in the dichromate ion is $126^{\circ }$, so statement (D) is correct. The correct statements are (A), (C) and (D).