Waec Model Questions Vol1 2020 Chemistry Question 42

Practice objective / multiple choice question 42 from the 2020 Waec Model Questions Vol1 Chemistry examination.

Waec Model Questions Vol1 2020 Chemistry Objective / Multiple Choice Hard Difficulty
Question 42 WAEC_MODEL_QUESTIONS_VOL1 • 2020 • CHEMISTRY • objective

An alloy of metals A and B has a measured density of 8.5 g cm⁻³. Pure metal A has density 10.0 g cm⁻³ and metal B 7.0 g cm⁻³. A cylindrical rod of the alloy 10.00 cm long and mass 85.0 g is heated uniformly, its length increasing by 0.20 %. The linear expansion coefficient of the alloy is α = 2.0 × 10⁻⁵ °C⁻¹. (i) Determine the temperature rise ΔT that caused the observed expansion. (ii) Assuming isotropic expansion, calculate the new density of the rod after heating. (iii) Using the original density, find the mass percent of metal A in the alloy.

Answer Options

A. ΔT = 90 °C; new density ≈ 8.48 g cm⁻³; mass percent of A ≈ 55.0 %
B. ΔT = 95 °C; new density ≈ 8.44 g cm⁻³; mass percent of A ≈ 57.0 %
C. ΔT = 110 °C; new density ≈ 8.42 g cm⁻³; mass percent of A ≈ 62.0 %
Correct Answer D. ΔT = 100 °C; new density ≈ 8.45 g cm⁻³; mass percent of A ≈ 58.8 %
Correct Answer
D
Correct Option:
ΔT = 100 °C; new density ≈ 8.45 g cm⁻³; mass percent of A ≈ 58.8 %

About This Question

This is Waec Model Questions Vol1 2020 Chemistry Question 42. It is one of the objective questions from the 2020 Waec Model Questions Vol1 Chemistry examination.

Difficulty level: Hard .

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