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Saturday, 31 October

JEE Main 2021 · ChemistryMultiple choiceSingle correctMediumConceptual

JEE Main 31 August 2021, Shift 2, Chemistry Q31

Question 31 of 90 in this shift, Chemistry question 1 of 30, Section A.

The incorrect expression among the following is :
  1. (1)ΔGSystemΔSTotal=−T\frac{\Delta G_{System}}{\Delta S_{Total}} = -T (at constant P)
  2. (2)For isothermal process wreversible=−nRT ln⁡VfViw_{reversible} = -nRT\ \ln\frac{V_f}{V_i}
  3. (3)ln⁡K=ΔH∘−TΔS∘RT\ln K = \frac{\Delta H^\circ - T\Delta S^\circ}{RT}Official answer
  4. (4)K=e−ΔG∘/RTK = e^{-\Delta G^\circ/RT}

Official answer

Option 3

NTA final key.

Chapter
Thermodynamics (Chemistry)
Topic
Gibbs Free Energy
Idea tested
Gibbs Energy and Equil

Same idea in other shifts

Asked 10× in all
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  2. 6 Apr 2026, Shift 1 · Q75Consider the reaction X⇌Y\mathrm{X\rightleftharpoons Y} at 300 K. If ΔHθ\Delta H^\theta and K are 28.40 kJ mol−1^{-1} and 1.8×10−71.8\times10^{-7}…MediumNumerical value
  3. 1 Feb 2024, Shift 2 · Q82For a certain reaction at 300K, K = 10, then ΔG∘\Delta G^\circ for the same reaction is −- ________ ×10−1\times 10^{-1} kJ mol−1^{-1}. (Given…EasyNumerical value
  4. 31 Jan 2024, Shift 1 · Q84Consider the following reaction at 298 K. 32O2(g)⇌O3(g)\frac{3}{2}\mathrm{O_{2(g)}} \rightleftharpoons \mathrm{O_{3(g)}}.…EasyNumerical value
  5. 6 Apr 2023, Shift 1 · Q84The value of log K for the reaction A⇌B\mathrm{A \rightleftharpoons B} at 298 K is ________. (Nearest integer) Given:…MediumNumerical value
  6. 24 Jun 2022, Shift 1 · Q822O3(g)⇌3O2(g)\mathrm{2O_3(g)\rightleftharpoons 3O_2(g)} At 300 K, ozone is fifty percent dissociated. The standard free energy change at this…MediumNumerical value
  7. 25 Jun 2022, Shift 1 · Q84The standard entropy change for the reaction 4Fe(s)+3O2(g)→2Fe2O3(s)4\mathrm{Fe(s)} + 3\mathrm{O_2(g)} \rightarrow 2\mathrm{Fe_2O_3(s)} is…EasyNumerical value
  8. 26 Jun 2022, Shift 2 · Q8640% of HI undergoes decompostion to H2\mathrm{H_2} and I2\mathrm{I_2} at 300 K. ΔG⊖\Delta G^\ominus for this decompostion reaction at one…MediumNumerical value

Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.