Neco 2022 Chemistry Question 18

Practice objective / multiple choice question 18 from the 2022 Neco Chemistry examination.

Neco 2022 Chemistry Objective / Multiple Choice Hard Difficulty

Question 18 NECO • 2022 • CHEMISTRY • objective

A wastewater treatment plant reduces the concentration of a biodegradable pollutant following first‑order kinetics \( C = C_0 e^{-kt}\). The plant operates with a hydraulic retention time of 6 h. Influent concentration \(C_0 = 120\ \text{mg L}^{-1}\). Discharge standard requires \(C \le 30\ \text{mg L}^{-1}\). (a) Find the minimum rate constant \(k\) (h^{-1}) needed. (b) If the plant can achieve \(k = 0.45\ \text{h}^{-1}\), calculate the percentage by which the effluent concentration is lower than the standard.

A. 0.183 h^{-1}, 68.5 %

B. 0.277 h^{-1}, 73.1 %

Correct Answer C. 0.231 h^{-1}, 73.1 %

D. 0.231 h^{-1}, 93.4 %

Correct Answer

Correct Option:

0.231 h^{-1}, 73.1 %

This is Neco 2022 Chemistry Question 18. It is one of the objective questions from the 2022 Neco Chemistry examination.

Difficulty level: Hard .

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