JEE Main 2026 — 4 April, Morning Shift — Question 58

(A) $\mathrm{MnO_4^-} + \mathrm{Fe^{2+}} + \mathrm{H^+} \longrightarrow \mathrm{Fe^{3+}} + \mathrm{Mn^{2+}} + \mathrm{H_2O}$

(B) $\mathrm{Na_2Cr_2O_7}$ generally not used as a primary standard in volumetric analysis because it is deliquescent.

(C) In acidic medium $\mathrm{Cr_2O_7^{2-}}$ exists and it gets converted into $\mathrm{CrO_4^{2-}}$ in basic medium.

$2\mathrm{CrO_4^{2-}} + 2\mathrm{H^+} \longrightarrow \mathrm{Cr_2O_7^{2-}} + \mathrm{H_2O}$

$\mathrm{Cr_2O_7^{2-}} + 2\mathrm{OH^-} \longrightarrow 2\mathrm{CrO_4^{2-}} + \mathrm{H_2O}$

(D) $\mathrm{K_2Cr_2O_7}$ is a good oxidising agent and bond angle of $\mathrm{Cr-O-Cr}$ bond in $\mathrm{Cr_2O_7^{2-}}$ is $126^\circ$.