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JEE MAIN 2026
23-01-2026 S2
Question
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. $$ \begin{aligned} & \mathrm{PbO}_2+\mathrm{Pb} \rightarrow 2 \mathrm{PbO} ; \Delta_{\mathrm{r}} \mathrm{G}^{\circ}(1) \\ & \mathrm{SnO}_2+\mathrm{Sn} \rightarrow 2 \mathrm{SnO} ; \Delta_{\mathrm{r}} \mathrm{G}^{\circ}(2) \end{aligned} $$ Identify the correct set from the following
Select the correct option:
A
$\Delta_{\mathrm{r}} \mathrm{G}^{\circ}(1)>0 ; \Delta_{\mathrm{r}} \mathrm{G}^{\circ}(2)<0$
B
$\Delta_{\mathrm{r}} \mathrm{G}^{\circ}(1)<0 ; \Delta_{\mathrm{r}} \mathrm{G}^{\circ}(2)<0$
C
$\Delta_{\mathrm{r}} \mathrm{G}^{\circ}(1)<0 ; \Delta_{\mathrm{r}} \mathrm{G}^{\circ}(2)>0$
D
$\Delta_{\mathrm{r}} \mathrm{G}^{\circ}(1)>0 ; \Delta_{\mathrm{r}}^{\circ}(2)>0$
✓ Correct! Well done.
✗ Incorrect. Try again or view the solution.
Solution
$$ \mathrm{PbO}_2+\mathrm{Pb} \rightarrow 2 \mathrm{PbO} $$ $\mathrm{Pb}^{2+}$ is more stable hence reaction will be spontaneous. So $\Delta \mathrm{G}^{\circ}(1)$ is negative. $$ \mathrm{SnO}_2+\mathrm{Sn} \rightarrow 2 \mathrm{SnO} $$ $\mathrm{Sn}^{+2}$ is less stable, so reaction will be nonspontaneous hance $\Delta \mathrm{G}_{\mathrm{r}}^{\circ}(2)$ is positive.
Question Tags
JEE Main
Chemistry
Medium
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