Waec Model Questions Vol1 2019 Chemistry Question 20

Practice objective / multiple choice question 20 from the 2019 Waec Model Questions Vol1 Chemistry examination.

Waec Model Questions Vol1 2019 Chemistry Objective / Multiple Choice Hard Difficulty
Question 20 WAEC_MODEL_QUESTIONS_VOL1 • 2019 • CHEMISTRY • objective

A lake has a volume of 1.5×10⁹ L and a surface area of 2.0×10⁶ m². The water temperature is 25 °C. The Henry's law constant for carbon monoxide (CO) at this temperature is H = 9.0×10⁻⁴ mol·L⁻¹·atm⁻¹. The partial pressure of CO in the atmosphere above the lake is 0.0001 atm. Assuming equilibrium between the lake water and the atmosphere, calculate (a) the total mass of CO (in grams) dissolved in the lake, and (b) the concentration of dissolved CO (in mg·L⁻¹) after 10 days if CO is consumed in the lake by a first‑order reaction with rate constant k = 0.02 day⁻¹.

Answer Options

A. Initial mass = 2.10×10^3 g; concentration after 10 days = 0.0035 mg\/L
B. Initial mass = 4.56×10^3 g; concentration after 10 days = 0.0012 mg\/L
Correct Answer C. Initial mass = 3.78×10^3 g; concentration after 10 days = 0.0021 mg/L
D. Initial mass = 3.78×10^2 g; concentration after 10 days = 0.021 mg\/L
Correct Answer
C
Correct Option:
Initial mass = 3.78×10^3 g; concentration after 10 days = 0.0021 mg/L

About This Question

This is Waec Model Questions Vol1 2019 Chemistry Question 20. It is a objective / multiple choice question from the 2019 Waec Model Questions Vol1 Chemistry examination.

Difficulty level: Hard .

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