Chemical Oxygen Demand (COD) is a measure of

AInorganic matters in water

BAll chemicals present in water

CAll organic matters in water ✓ Correct

DOnly some specific organic matters in water

Correct answer: (C) All organic matters in water

Explanation

Chemical oxygen demand measures essentially all organic matter in water.

It is not confined to inorganic matter, which is not what the test targets.

It does not cover every chemical present, only oxidisable organic material.

It is not limited to a few specific organic substances but spans them broadly.

The test uses a strong oxidant to break down organic content and gauges oxygen used.

Biochemical oxygen demand, by contrast, measures only the biodegradable fraction.

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