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Saturday, 31 October

JEE Main 2021 · ChemistryNumerical answerNumerical valueEasyCalculation

JEE Main 25 February 2021, Shift 1, Chemistry Q57

Question 57 of 90 in this shift, Chemistry question 27 of 30, Section B.

The ionization enthalpy of Na+\mathrm{Na^+} formation from Na(g)\mathrm{Na_{(g)}} is 495.8 kJ mol−1^{-1}, while the electron gain enthalpy of Br is −325.0-325.0 kJ mol−1^{-1}. Given the lattice enthalpy of NaBr is −728.4-728.4 kJ mol−1^{-1}. The energy for the formation of NaBr ionic solid is (-)________ ×10−1\times10^{-1} kJ mol−1^{-1}.

Official answer

5576

NTA final key.

Chapter
Classification of Elements and Periodicity in Properties
Topic
Enthalpy and Hess's Law
Idea tested
Born-Haber Cycle for Lattice Enthalpy

Same idea in other shifts

Asked 2× in all
  1. 26 Aug 2021, Shift 1 · Q53The Born-Haber cycle for KCl is evaluated with the following data : ΔfH⊖\Delta_f \mathrm{H}^{\ominus} for KCl =−436.7= -436.7 kJ mol−1^{-1};…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.