Igcse Model Questions Vol1 2025 Chemistry Question 29

Practice objective / multiple choice question 29 from the 2025 Igcse Model Questions Vol1 Chemistry examination.

Igcse Model Questions Vol1 2025 Chemistry Objective / Multiple Choice Hard Difficulty
Question 29 IGCSE_MODEL_QUESTIONS_VOL1 • 2025 • CHEMISTRY • objective

A step‑growth polymer is formed from a diacid (M = 120 g mol⁻¹) and a diamine (M = 100 g mol⁻¹) in equimolar amounts. Each condensation releases one molecule of water (18 g mol⁻¹). After polymerisation the number‑average degree of polymerisation (DPₙ) is 250. (a) Calculate the number‑average molecular weight (Mₙ) of the polymer. (b) If the polymer sample contains 0.020 mol of repeat units, determine its mass. (c) The polymer is cross‑linked, increasing its density from 1.10 g cm⁻³ to 1.25 g cm⁻³ while the mass stays the same. Calculate the percentage decrease in volume.

Answer Options

A. Mₙ = 5.05×10⁴ g mol⁻¹; Mass = 4.50 g; Volume decrease = 12.0 %
B. Mₙ = 5.50×10⁴ g mol⁻¹; Mass = 4.04 g; Volume decrease = 15.0 %
Correct Answer C. Mₙ = 5.05×10⁴ g mol⁻¹; Mass = 4.04 g; Volume decrease = 12.0 %
D. Mₙ = 4.80×10⁴ g mol⁻¹; Mass = 3.80 g; Volume decrease = 10.0 %
Correct Answer
C
Correct Option:
Mₙ = 5.05×10⁴ g mol⁻¹; Mass = 4.04 g; Volume decrease = 12.0 %

About This Question

This is Igcse Model Questions Vol1 2025 Chemistry Question 29. It is one of the objective questions from the 2025 Igcse Model Questions Vol1 Chemistry examination.

Difficulty level: Hard .

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