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Saturday, 31 October

JEE Main 2023 · ChemistryNumerical answerNumerical valueMediumCalculation

JEE Main 11 April 2023, Shift 1, Chemistry Q83

Question 83 of 90 in this shift, Chemistry question 23 of 30, Section B.

Solid fuel used in rocket is a mixture of Fe2O3\mathrm{Fe_2O_3} and Al (in ratio 1:2). The heat evolved (kJ) per gram of the mixture is __________ (Nearest integer) Given: ΔHfθ(Al2O3)=−1700 kJ mol−1\Delta \mathrm{H_f^{\theta}(Al_2O_3)} = -1700\ \mathrm{kJ\ mol^{-1}} ΔHfθ(Fe2O3)=−840 kJ mol−1\Delta \mathrm{H_f^{\theta}(Fe_2O_3)} = -840\ \mathrm{kJ\ mol^{-1}} Molar mass of Fe, Al and O are 56, 27 and 16 g mol−1\mathrm{g\ mol^{-1}} respectively

Official answer

4

NTA final key.

Chapter
Thermodynamics (Chemistry)
Topic
Enthalpy and Hess's Law
Idea tested
Standard Enthalpy of Reaction

Same idea in other shifts

Asked 2× in all
  1. 17 Mar 2021, Shift 1 · Q54The standard enthalpies of formation of Al2O3\mathrm{Al_2O_3} and CaO are −1675 kJ mol−1-1675\ \mathrm{kJ\ mol^{-1}} and −635 kJ mol−1-635\ \mathrm{kJ\ mol^{-1}}…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. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.