The Winkler method is used to determine:
- AOrganic carbon
- BElemental carbon
- CDissolved oxygen
- DBiochemical oxygen demand
Show answer and explanation
Correct answer: (c) Dissolved oxygen
Explanation
The Winkler method measures the dissolved oxygen (DO) in a water sample. The oxygen is fixed by manganese(II) salts in alkaline solution; acid then releases an equal amount of iodine, which is measured by titration with sodium thiosulphate.
Biochemical oxygen demand (BOD) uses this method: the dissolved oxygen is measured before and after the sample is kept for 5 days. But the method itself measures dissolved oxygen.