Waec Model Questions Vol1 2023 Chemistry Question 20

Practice objective / multiple choice question 20 from the 2023 Waec Model Questions Vol1 Chemistry examination.

Waec Model Questions Vol1 2023 Chemistry Objective / Multiple Choice Hard Difficulty
Question 20 WAEC_MODEL_QUESTIONS_VOL1 • 2023 • CHEMISTRY • objective

A polyester is formed by condensation of monomer A (C₂H₄O₂, M = 60 g mol⁻¹) and monomer B (C₃H₆O, M = 58 g mol⁻¹) in a 1:1 molar ratio, losing one molecule of water (M = 18 g mol⁻¹) per repeating unit. A sample of the polymer has a number‑average molecular weight of 1.20 × 10⁵ g mol⁻¹. (i) Determine the average degree of polymerisation (DP). (ii) If each repeating unit releases 0.5 kJ upon combustion, calculate the heat of combustion per gram of polymer. Give DP as a whole number and the heat of combustion in J g⁻¹ to the nearest whole number.

Answer Options

A. DP = 1300; heat of combustion = 6 J g⁻¹
B. DP = 1500; heat of combustion = 10 J g⁻¹
Correct Answer C. DP = 1200; heat of combustion = 5 J g⁻¹
D. DP = 1000; heat of combustion = 4 J g⁻¹
Correct Answer
C
Correct Option:
DP = 1200; heat of combustion = 5 J g⁻¹

About This Question

This is Waec Model Questions Vol1 2023 Chemistry Question 20. It is one of the objective questions from the 2023 Waec Model Questions Vol1 Chemistry examination.

Difficulty level: Hard .

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