It is noticed that $\mathrm{Pb}^{2+}$ is more stable than $\mathrm{Pb}^{4+}$ but $\mathrm{Sn}^{2+}$ is less stable than $\mathrm{Sn}^{4+}$. Observe the following reactions $\mathrm{PbO}_{2}+\mathrm{Pb} \rightarrow 2 \mathrm{PbO} ; \Delta_{\mathrm{r}} \mathrm{G}^{\circ}(1)$ $\mathrm{SnO}_{2}+\mathrm{Sn} \rightarrow 2 \mathrm{SnO} ; \Delta_{\mathrm{r}} \mathrm{G}^{\circ}(2)$ Identify the correct set from the following.

(C) $\Delta_{\mathrm{r}} \mathrm{G}^{\circ}(1) 0$

(A) $\Delta_{\mathrm{r}} \mathrm{G}^{\circ}(1)>0 ; \Delta_{\mathrm{r}} \mathrm{G}^{\circ}(2)<0$

(B) $\Delta_{\mathrm{r}} \mathrm{G}^{\circ}(1)<0 ; \Delta_{\mathrm{r}} \mathrm{G}^{\circ}(2)<0$

(D) $\Delta_{\mathrm{r}} \mathrm{G}^{\circ}(1)>0 ; \Delta_{\mathrm{r}} \mathrm{G}^{\circ}(2)>0$

JEE Main · 2026 · 23 Jan 2026 · Shift 2 · Chemical Thermodynamics

It is noticed that

Pb^{2 +}

is more stable than

Pb^{4 +}

but

Sn^{2 +}

is less stable than

Sn^{4 +}

. Observe the following reactions

PbO_{2} + Pb \to 2 PbO; Δ_{r} G^{\circ} (1)

SnO_{2} + Sn \to 2 SnO; Δ_{r} G^{\circ} (2)

Identify the correct set from the following.

Answer: (C)

Because Pb

^{2 +}

is more stable than Pb

^{4 +}

, converting the Pb

^{4 +}

of PbO

_{2}

(with metallic Pb) into the Pb

^{2 +}

of PbO is thermodynamically favourable, so

Δ_{r} G^{\circ} (1) < 0

. For tin the order is reversed, Sn

^{4 +}

being more stable than Sn

^{2 +}

, so forming SnO from SnO

_{2}

and Sn is non-spontaneous and

Δ_{r} G^{\circ} (2) > 0

. Hence

Δ_{r} G^{\circ} (1) < 0

and

Δ_{r} G^{\circ} (2) > 0

JEE Main · 2026 · 23 Jan 2026 · Shift 2 · Single correct option