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Saturday, 31 October

JEE Main 2021 · ChemistryNumerical answerNumerical valueMediumCalculation

JEE Main 27 August 2021, Shift 2, Chemistry Q55

Question 55 of 90 in this shift, Chemistry question 25 of 30, Section B.

Data given for the following reaction is as follows : FeO(s)+C(graphite)⟶Fe(s)+CO(g)\mathrm{FeO_{(s)} + C_{(graphite)} \longrightarrow Fe_{(s)} + CO_{(g)}} Table (Substance : ΔfH∘\Delta_f H^\circ (kJ mol−1\mathrm{kJ\ mol^{-1}}) ; ΔS∘\Delta S^\circ (J mol−1 K−1\mathrm{J\ mol^{-1}\ K^{-1}})) : FeO(s)\mathrm{FeO_{(s)}} : −266.3-266.3 ; 57.4957.49 C(graphite)\mathrm{C_{(graphite)}} : 00 ; 5.745.74 Fe(s)\mathrm{Fe_{(s)}} : 00 ; 27.2827.28 CO(g)\mathrm{CO_{(g)}} : −110.5-110.5 ; 197.6197.6 The minimum temperature in K at which the reaction becomes spontaneous is __________. (Integer answer)

The figure, in words

A 4-row data table: substance, standard enthalpy of formation (kJ mol^-1) and standard entropy (J mol^-1 K^-1) for FeO(s), C(graphite), Fe(s), CO(g).

Official answer

964

NTA final key.

Chapter
Thermodynamics (Chemistry)
Topic
Gibbs Free Energy
Idea tested
Temperature Dependence

Same idea in other shifts

Asked 3× in all
  1. 6 Apr 2024, Shift 2 · Q83For the reaction at 298 K, 2A+B→C2A + B \rightarrow C, ΔH=400\Delta H = 400 kJ mol−1^{-1} and ΔS=0.2\Delta S = 0.2 kJ mol−1^{-1} K−1^{-1}. The…EasyNumerical value
  2. 26 Feb 2021, Shift 1 · Q53For a chemical reaction A+B⇌C+D\mathrm{A + B \rightleftharpoons C + D} (ΔrH⊖=80\Delta_r H^{\ominus} = 80 kJ mol−1^{-1}) the entropy change…EasyNumerical 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. This question needs a figure we do not reproduce; it is described in words above. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.