Neco Model Questions Vol1 2024 Chemistry Question 11
Practice objective / multiple choice question 11 from the 2024 Neco Model Questions Vol1 Chemistry examination.
A wastewater contains phenol at a concentration of 150 mg L^{-1}. It is treated aerobically, where phenol degrades following first‑order kinetics with a rate constant \(k = 0.12\ \text{day}^{-1}\) at 25 °C. After treatment, the water is mixed with river water (phenol concentration negligible) in a volume ratio of 1 : 3 (treated : river) before discharge. The permissible phenol limit for discharge is 10 mg L^{-1}. Determine the minimum treatment time (in days) required so that, after mixing, the phenol concentration does not exceed the limit. Give your answer to two decimal places.
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This is Neco Model Questions Vol1 2024 Chemistry Question 11. It is one of the objective questions from the 2024 Neco Model Questions Vol1 Chemistry examination.
Difficulty level: Hard .
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