Verified Solution • 2025–26 Session moderate QJEEM25Ch70bc: JEE Main 2025 Chemistry - Class 11 JEEM25Ch70bc Solution: The heat of formation of is given by : amp;S( g)+32O2( g)→SO3( g)+2xkcalamp;SO2( g)+12O2( g)→SO3( g)+ykcal\begin{aligned}& \mathrm{S}(\mathrm{~g})+\frac{3}{2} \mathrm{O}_2(\mathrm{~g}) \rightarrow \mathrm{SO}_3(\mathrm{~g})+2 x \mathrm{kcal} \\& \mathrm{SO}_2(\mathrm{~g})+\frac{1}{2} \mathrm{O}_2(\mathrm{~g}) \rightarrow \mathrm{SO}_3(\mathrm{~g})+y \mathrm{kcal}\end{aligned}amp;S( g)+23O2( g)→SO3( g)+2xkcalamp;SO2( g)+21O2( g)→SO3( g)+ykcal The heat of formation of SO2( g)\mathrm{SO}_2(\mathrm{~g})SO2( g) is given by : Multiple Choice Options A 2x+y2 x+y2x+y kcal B 2xy kcal\frac{2 x}{y} \mathrm{~kcal}y2x kcal C y−2x kcaly-2 x \mathrm{~kcal}y−2x kcal D x+y kcalx+y \mathrm{~kcal}x+y kcal Step-by-Step Verified Solution SO2(g)+12O2( g)⟶SO3( g)ΔH=−y\underset{(\mathrm{g})}{\mathrm{SO}_2}+\frac{1}{2} \underset{(\mathrm{~g})}{\mathrm{O}_2} \longrightarrow \underset{(\mathrm{~g})}{\mathrm{SO}_3} \quad \Delta \mathrm{H}=-\mathrm{y}(g)SO2+21( g)O2⟶( g)SO3ΔH=−y amp;amp;ΔHr=(ΔHf)SO3−(ΔHf)SO2amp;−y=−2x−(ΔHf)SO2amp;(ΔHf)SO2=y−2xamp; Option (2) \begin{aligned}&\begin{aligned}& \Delta \mathrm{H}_{\mathrm{r}}=\left(\Delta \mathrm{H}_{\mathrm{f}}\right)_{\mathrm{SO}_3}-\left(\Delta \mathrm{H}_{\mathrm{f}}\right)_{\mathrm{SO}_2} \\& -\mathrm{y}=-2 \mathrm{x}-\left(\Delta \mathrm{H}_{\mathrm{f}}\right)_{\mathrm{SO}_2} \\& \left(\Delta \mathrm{H}_{\mathrm{f}}\right)_{\mathrm{SO}_2}=\mathrm{y}-2 \mathrm{x}\end{aligned}\\&\text { Option (2) }\end{aligned}amp;amp;ΔHr=(ΔHf)SO3−(ΔHf)SO2amp;−y=−2x−(ΔHf)SO2amp;(ΔHf)SO2=y−2xamp; Option (2) Related Learning Resources & Exam Preparation JEE Main PYQ Question Bank Browse year-wise authentic previous years' questions with solutions Authentic CBT Mock Tests Simulate official exam environment with live timer and percentile scoring