It is noticed that Pb 2+ is more stable than Pb 2+ but Sn 2+ is less stable than Sn 4+ . Observe the following reactions begin gathered PbO 2 + Pb rightarrow 2 PbO ; Δ r G ° end gathered begin gathered SnO 2 + Sn rightarrow 2 SnO ; Δ r G ° end gathered Identify the correct set from the following.

Δ r G ° (1)<0 ; Δ r G ° (2) 0

Δ r G ° (1) 0 ; Δ r G ° (2)<0

Δ r G ° (1)<0 ; Δ r G ° (2)<0

Δ r G ° (1) 0 ; Δ r G ° (2) 0

Chemistry · Thermodynamics & Thermochemistry

JEE Main 2026 — 23 January, Evening Shift — Question 47

It is noticed that $\mathrm{Pb}^{2+}$ is more stable than $\mathrm{Pb}^{2+}$ 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} \end{gathered}$$ $$\begin{gathered} \mathrm{SnO}_{2}+\mathrm{Sn} \rightarrow 2 \mathrm{SnO} ; \Delta_{\mathrm{r}} \mathrm{G}^{\circ} \end{gathered}$$ Identify the correct set from the following.

Option A:
$\Delta_{\mathrm{r}} \mathrm{G}^{\circ}(1)>0 ; \Delta_{\mathrm{r}} \mathrm{G}^{\circ}(2)<0$
Option B:
$\Delta_{\mathrm{r}} \mathrm{G}^{\circ}(1)<0 ; \Delta_{\mathrm{r}} \mathrm{G}^{\circ}(2)<0$
Option C:
$\Delta_{\mathrm{r}} \mathrm{G}^{\circ}(1)<0 ; \Delta_{\mathrm{r}} \mathrm{G}^{\circ}(2)>0$
Correct
Option D:
$\Delta_{\mathrm{r}} \mathrm{G}^{\circ}(1)>0 ; \Delta_{\mathrm{r}} \mathrm{G}^{\circ}(2)>0$

Answer: C

Step-by-step solution

$\mathrm{PbO}_{2}+\mathrm{Pb} \rightarrow 2 \mathrm{PbO}$ $\mathrm{Pb}^{2+}$ is more stable hence reaction will be spontaneous. So $\Delta \mathrm{G}^{\circ}{ }_{\mathrm{r}}(1)$ is negative. $\mathrm{SnO}_{2}+\mathrm{Sn} \rightarrow 2 \mathrm{SnO}$ $\mathrm{Sn}^{+2}$ is less stable, so reaction will be nonspontaneous hance $\Delta \mathrm{G}^{\circ}{ }_{\mathrm{r}}(2)$ is positive.

Answer key and solution verified before publishing.

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Exam: JEE Main 2026
Paper: 23 January, Evening Shift
Subject: Chemistry
Chapter: Thermodynamics & Thermochemistry
Topic: Gibbs Free Energy - Relation with Equilibrium, Metallurgy and Electrochemistry