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Saturday, 31 October

JEE Main 2025 · ChemistryMultiple choiceSingle correctMediumConceptual

JEE Main 7 April 2025, Shift 2, Chemistry Q55

Question 55 of 75 in this shift, Chemistry question 5 of 25, Section A.

Liquid A and B form an ideal solution. The vapour pressures of pure liquids A and B are 350 and 750 mm Hg respectively at the same temperature. If xAx_A and xBx_B are the mole fraction of A and B in solution while yAy_A and yBy_B are the mole fraction of A and B in vapour phase then,
  1. (1)xAxB>yAyB\frac{x_A}{x_B}>\frac{y_A}{y_B}Official answer
  2. (2)xAxB=yAyB\frac{x_A}{x_B}=\frac{y_A}{y_B}
  3. (3)(xA−yA)<(xB−yB)(x_A-y_A)<(x_B-y_B)
  4. (4)xAxB<yAyB\frac{x_A}{x_B}<\frac{y_A}{y_B}

Official answer

Option 1

NTA final key.

Chapter
Solutions
Topic
Colligative Properties
Idea tested
Relative Lowering of VP

Same idea in other shifts

Asked 12× in all
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  5. 11 Apr 2023, Shift 2 · Q62What weight of glucose must be dissolved in 100 g of water to lower the vapour pressure by 0.20 mm Hg ? (Assume dilute solution is being…MediumSingle correct
  6. 15 Apr 2023, Shift 1 · Q83The vapour pressure of 30% (w/v) aqueous solution of glucose is __________ mm Hg at 25∘C25^\circ\mathrm{C}. [Given : The density of 30%…MediumNumerical value
  7. 28 Jun 2022, Shift 1 · Q85The vapour pressures of two volatile liquids A and B at 25°C are 50 Torr and 100 Torr, respectively. If the liquid mixture contains 0.3…MediumNumerical value
  8. 26 Feb 2021, Shift 1 · Q54224 mL of SO2(g)\mathrm{SO_{2(g)}} at 298 K and 1 atm is passed through 100 mL of 0.1 M NaOH solution. The non-volatile solute produced is…HardNumerical 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.