Waec Model Questions Vol1 2020 Chemistry Question 27

Practice objective / multiple choice question 27 from the 2020 Waec Model Questions Vol1 Chemistry examination.

Waec Model Questions Vol1 2020 Chemistry Objective / Multiple Choice Hard Difficulty
Question 27 WAEC_MODEL_QUESTIONS_VOL1 • 2020 • CHEMISTRY • objective

A factory discharges effluent at a rate of 2 000 L day⁻¹ containing 0.05 mg L⁻¹ phenol into a river that flows at 5.0×10⁵ L day⁻¹ with an upstream phenol concentration of 0.005 mg L⁻¹. After complete mixing, the phenol concentration downstream, measured 2 days later (the travel time for water to reach that point), is 0.003 mg L⁻¹. Assuming first‑order natural degradation of phenol in the river segment, determine (a) the first‑order rate constant k (day⁻¹), (b) the phenol concentration after 5 days of travel, and (c) the percentage removal of phenol after those 5 days. Give k to two significant figures and concentrations to three significant figures.

Answer Options

Correct Answer A. k = 0.27 day⁻¹; C(5 days) ≈ 0.0013 mg L⁻¹; removal ≈ 75 %
B. k = 0.33 day⁻¹; C(5 days) ≈ 0.0010 mg L⁻¹; removal ≈ 80 %
C. k = 0.18 day⁻¹; C(5 days) ≈ 0.0019 mg L⁻¹; removal ≈ 55 %
D. k = 0.22 day⁻¹; C(5 days) ≈ 0.0016 mg L⁻¹; removal ≈ 68 %
Correct Answer
A
Correct Option:
k = 0.27 day⁻¹; C(5 days) ≈ 0.0013 mg L⁻¹; removal ≈ 75 %

About This Question

This is Waec Model Questions Vol1 2020 Chemistry Question 27. It is one of the objective questions from the 2020 Waec Model Questions Vol1 Chemistry examination.

Difficulty level: Hard .

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