Question

Water pollution of a river is measured by __________.

• A. amount of chlorine dissolved in water
• B. amount of ozone dissolved in water
• C. amount of nitrogen dissolved in water
• D. amount of oxygen dissolved in water

Answer 1

The correct option is D amount of oxygen dissolved in water

Biochemical oxygen demand is a measure of how much dissolved oxygen is being consumed as microbes break down organic matter. A high oxygen demand, therefore indicates that levels of dissolved oxygen are falling, with potentially dangerous implications for the river's biodiversity. High biochemical oxygen demand can be caused by high levels of organic pollution. Thus the correct answer is option D.