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 one of the objective questions from the 2020 Waec Model Questions Vol1 Chemistry examination.

Difficulty level: Hard .

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