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Saturday, 31 October

JEE Main 2024 · ChemistryNumerical answerNumerical valueMediumMulti-step

JEE Main 6 April 2024, Shift 2, Chemistry Q84

Question 84 of 90 in this shift, Chemistry question 24 of 30, Section B.

When 'xx' ×10−2\times 10^{-2} mL methanol (molar mass =32= 32 g; density =0.792= 0.792 g/cm3^3) is added to 100 mL water (density =1= 1 g/cm3^3), the following diagram is obtained. x=x = ________ (nearest integer). [Given : Molal freezing point depression constant of water at 273.15 K is 1.86 K kg mol−1^{-1}]

The figure, in words

Vapour pressure vs temperature/K graph: curves for water, methanolic solution and frozen system; freezing points marked at 270.65 K (solution) and 273.15 K (water).

Official answer

543

NTA final key.

Chapter
Solutions
Topic
Colligative Properties
Idea tested
Freezing Point Depression

Same idea in other shifts

Asked 16× in all
  1. 4 Apr 2024, Shift 2 · Q842.7 kg of each of water and acetic acid are mixed. The freezing point of the solution will be -x °C. Consider the acetic acid does not…MediumNumerical value
  2. 5 Apr 2024, Shift 2 · Q84Considering acetic acid dissociates in water, its dissociation constant is 6.25×10−56.25\times10^{-5}. If 5 mL of acetic acid is dissolved in 1…HardNumerical value
  3. 30 Jan 2024, Shift 1 · Q63What happens to freezing point of benzene when small quantity of napthalene is added to benzene ?EasySingle correct
  4. 25 Jul 2022, Shift 2 · Q62Two solutions A and B are prepared by dissolving 1 g of non-volatile solutes X and Y, respectively in 1 kg of water. The ratio of…EasySingle correct
  5. 28 Jul 2022, Shift 1 · Q84150 g of acetic acid was contaminated with 10.2 g ascorbic acid (C6H8O6\mathrm{C_6H_8O_6}) to lower down its freezing point by…EasyNumerical value
  6. 30 Jul 2022, Shift 2 · Q5331 g of ethylene glycol is mixed with 500 g of water. The freezing point of the aqueous solution is ________ K. (in nearest integer)…EasyNumerical value
  7. 3 Aug 2021, Shift 2 · Q32The lowest freezing point among the following solutions will be observed in [Atomic weight : C = 12, Mg = 24, Na = 23, Cl = 35.5, O = 16,…EasySingle correct
  8. 26 Aug 2021, Shift 2 · Q5483 g of ethylene glycol dissolved in 625 g of water. The freezing point of the solution is __________ K. (Nearest integer) [Use : Molal…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. 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.