Neco 2021 Chemistry Question 48

Practice objective / multiple choice question 48 from the 2021 Neco Chemistry examination.

Neco 2021 Chemistry Objective / Multiple Choice Hard Difficulty

Question 48 NECO • 2021 • CHEMISTRY • objective

A wastewater treatment plant receives 10,000 m³/day of effluent containing 150 mg/L of NH₃‑N and 80 mg/L of PO₄³⁻. The plant uses a two‑stage biological process: first nitrification converting NH₃ to NO₃⁻ with 90 % efficiency, then denitrification removing 85 % of the produced NO₃⁻ as N₂ gas. Simultaneously, a chemical precipitation step removes 70 % of PO₄³⁻ as calcium phosphate. Determine the final concentrations (in mg/L) of total nitrogen (as N) and phosphate (as PO₄³⁻) in the discharged water.

A. 22.5 mg/L, 24 mg/L

Correct Answer B. 35.25 mg/L, 24 mg/L

C. 35.25 mg/L, 56 mg/L

D. 20.25 mg/L, 24 mg/L

Correct Answer

Correct Option:

35.25 mg/L, 24 mg/L

This is Neco 2021 Chemistry Question 48. It is one of the objective questions from the 2021 Neco Chemistry examination.

Difficulty level: Hard .

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