Verified Solution • 2025–26 Session moderate

QJEEM17Ch9ab8: JEE Main 2017 Chemistry - Class 12 JEEM17Ch9ab8 Solution: The freezing point of benzene decreases by 0.45 0 C when 0.2 g…

The freezing point of benzene decreases by 0.450C when 0.2 g of acetic acid is added to 20g of benzene. If acetic acid associates to form a dimer in benzene, percentage association of acetic acid in benzene will be: (Kf for benzene = 5.12 K kg mol–1)

Multiple Choice Options

  • A 80.40%
  • B 74.60%
  • C 94.60%
  • D 64.60%

Step-by-Step Verified Solution

ΔTf = i × Kf × m

⇒ 0.45 = i × 5.12 × 0.2×100060×20

⇒ i = 0.527

2CH3COOH ⇌ (CH3COOH)2
      1 - α                   α2

i = 1 - α + α2

⇒ α = 0.946

∴ % dissociation is 94.6%.

Related Learning Resources & Exam Preparation

JEE Main PYQ Question Bank
Browse year-wise authentic previous years' questions with solutions
Authentic CBT Mock Tests
Simulate official exam environment with live timer and percentile scoring