Waec Model Questions Vol1 2020 Chemistry Question 25

Practice objective / multiple choice question 25 from the 2020 Waec Model Questions Vol1 Chemistry examination.

Waec Model Questions Vol1 2020 Chemistry Objective / Multiple Choice Hard Difficulty
Question 25 WAEC_MODEL_QUESTIONS_VOL1 • 2020 • CHEMISTRY • objective

A wastewater stream contains 150 mg L⁻¹ phenol. It undergoes aerobic biological treatment that follows first‑order kinetics with a rate constant k = 0.12 day⁻¹ at 25 °C. After 5 days, the effluent is further treated by an advanced oxidation process that reduces the remaining phenol concentration by 80 % in a single batch. Determine (a) the phenol concentration (mg L⁻¹) after both treatment steps and (b) the overall removal efficiency percentage. State whether the final concentration meets a discharge limit of 20 mg L⁻¹.

Answer Options

A. a) 18.0 mg L⁻¹; b) 88 % removal; meets the 20 mg L⁻¹ limit
Correct Answer B. a) 16.5 mg L⁻¹; b) 89 % removal; meets the 20 mg L⁻¹ limit
C. a) 14.2 mg L⁻¹; b) 90 % removal; exceeds the 20 mg L⁻¹ limit
D. a) 20.5 mg L⁻¹; b) 86 % removal; does not meet the 20 mg L⁻¹ limit
Correct Answer
B
Correct Option:
a) 16.5 mg L⁻¹; b) 89 % removal; meets the 20 mg L⁻¹ limit

About This Question

This is Waec Model Questions Vol1 2020 Chemistry Question 25. It is a objective / multiple choice question from the 2020 Waec Model Questions Vol1 Chemistry examination.

Difficulty level: Hard .

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