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Friday, 9 October

JEE Main 2025 · ChemistryMultiple choiceSingle correctMediumMulti-step

JEE Main 7 April 2025, Shift 1, Chemistry Q53

Question 53 of 75 in this shift, Chemistry question 3 of 25, Section A.

Total enthalpy change for freezing of 1 mol of water at 10∘10^\circC to ice at −10∘-10^\circC is __________ (Given: ΔfusH=x\Delta_{fus}H = x kJ/mol Cp[H2O(l)]=y J mol−1 K−1C_p[\mathrm{H_2O(l)}] = y\ \mathrm{J\,mol^{-1}\,K^{-1}} Cp[H2O(s)]=z J mol−1 K−1C_p[\mathrm{H_2O(s)}] = z\ \mathrm{J\,mol^{-1}\,K^{-1}}
  1. (1)−x−10y−10z-x - 10y - 10z
  2. (2)−10(100x+y+z)-10(100x + y + z)Official answer
  3. (3)10(100x+y+z)10(100x + y + z)
  4. (4)x−10y−10zx - 10y - 10z

Official answer

Option 2

NTA final key.

Chapter
Thermodynamics (Chemistry)
Topic
Enthalpy and Hess's Law
Idea tested
Enthalpy of Phase Transitions

Same idea in other shifts

Asked 3× in all
  1. 3 Apr 2025, Shift 2 · Q53Given below are two statements: Statement I : When a system containing ice in equilibrium with water (liquid) is heated, heat is absorbed…EasyTwo statements
  2. 29 Jun 2022, Shift 1 · Q8217.0 g of NH3\mathrm{NH_3} completely vapourises at −33.42∘C-33.42^\circ\mathrm{C} and 1 bar pressure and the enthalpy change in the process is…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 42 of the 174 JEE Main shifts held from 2017 to 2026.