Waec Model Questions Vol1 2025 Chemistry Question 45

Practice objective / multiple choice question 45 from the 2025 Waec Model Questions Vol1 Chemistry examination.

Waec Model Questions Vol1 2025 Chemistry Objective / Multiple Choice Medium Difficulty
Question 45 WAEC_MODEL_QUESTIONS_VOL1 • 2025 • CHEMISTRY • objective

A 2.00 g sample of a solid substance A is heated at constant pressure until it completely sublimates. The vapor pressure of A is 0.45 atm at 120 °C and 1.20 atm at 150 °C. Assuming the Clausius-Clapeyron equation applies, (a) calculate the enthalpy of sublimation (ΔH_sub) in kJ·mol⁻¹. (b) Estimate the temperature at which the vapor pressure would be 0.80 atm.

Answer Options

A. ΔH_sub ≈ 52 kJ·mol⁻¹; T ≈ 145 °C
B. ΔH_sub ≈ 38 kJ·mol⁻¹; T ≈ 130 °C
Correct Answer C. ΔH_sub ≈ 45 kJ·mol⁻¹; T ≈ 137 °C
D. ΔH_sub ≈ 60 kJ·mol⁻¹; T ≈ 150 °C
Correct Answer
C
Correct Option:
ΔH_sub ≈ 45 kJ·mol⁻¹; T ≈ 137 °C

About This Question

This is Waec Model Questions Vol1 2025 Chemistry Question 45. It is one of the objective questions from the 2025 Waec Model Questions Vol1 Chemistry examination.

Difficulty level: Medium .

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