Which of the following statements are correct? (A) The M3+/M2+ reduction potential for iron is greater than manganese.…

Analysing each statement:

A. $E°_{\text{Fe}^{3+}/\text{Fe}^{2+}} > E°_{\text{Mn}^{3+}/\text{Mn}^{2+}}$ — FALSE ✗

$E°_{\text{Fe}^{3+}/\text{Fe}^{2+}} = +0.77$ V; $E°_{\text{Mn}^{3+}/\text{Mn}^{2+}} = +1.57$ V

Mn³⁺/Mn²⁺ is greater, not Fe.

B. Higher O.S. stabilized by oxide ion — TRUE ✓

Oxide ion ($\text{O}^{2-}$) is a hard base and stabilizes high oxidation states of transition metals (e.g., $\text{MnO}_4^-$, $\text{CrO}_4^{2-}$, $\text{V}_2\text{O}_5$).

C. $\text{Cr}^{2+}$ liberates H₂ from dilute acid — TRUE ✓

$E°_{\text{Cr}^{3+}/\text{Cr}^{2+}} = -0.41$ V (negative) → $\text{Cr}^{2+}$ is a strong reducing agent and can reduce $\text{H}^+$ to $\text{H}_2$.

D. Magnetic moment of $\text{V}^{2+}$ between 4.4–5.2 BM — FALSE ✗

$\text{V}^{2+}$: $3d^3$, 3 unpaired electrons → $\mu = \sqrt{15} = 3.87$ BM (not in 4.4–5.2 range)

Correct: B and C

Answer: Option (1) — (B), (C) only