Igcse Model Questions Vol1 2017 Chemistry Question 7

Practice objective / multiple choice question 7 from the 2017 Igcse Model Questions Vol1 Chemistry examination.

Igcse Model Questions Vol1 2017 Chemistry Objective / Multiple Choice Hard Difficulty
Question 7 IGCSE_MODEL_QUESTIONS_VOL1 • 2017 • CHEMISTRY • objective

A river receives an effluent that initially contains 0.5 mg L⁻¹ of pesticide X. The pesticide degrades by first‑order kinetics with a half‑life of 12 days. After 3 days the water mixes with a clean tributary that dilutes the concentration to 60 % of its value at that moment. (a) Calculate the concentration of X after the 3 days and the dilution. (b) The safe limit for X is 0.05 mg L⁻¹. By what percentage must the concentration be further reduced to meet the limit?

Answer Options

Correct Answer A. 0.25 mg L⁻¹; additional 80 % reduction
B. 0.35 mg L⁻¹; additional 75 % reduction
C. 0.20 mg L⁻¹; additional 60 % reduction
D. 0.30 mg L⁻¹; additional 70 % reduction
Correct Answer
A
Correct Option:
0.25 mg L⁻¹; additional 80 % reduction

About This Question

This is Igcse Model Questions Vol1 2017 Chemistry Question 7. It is one of the objective questions from the 2017 Igcse Model Questions Vol1 Chemistry examination.

Difficulty level: Hard .

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