Which time frame is described for the BOD test in the notes?

• A. 60 minutes
• B. 1-2 hours
• C. 24 hours
• D. 5 days

Answer: (B)

Biochemical Oxygen Demand testing is used to estimate how much biodegradable organic matter is present by measuring the oxygen that microbes consume. In the notes you’re studying, the described time frame for performing the BOD test is one to two hours. The key here is to match what the notes state about the duration of the test steps, which is why that option fits best for this question.

It’s helpful to keep in mind that the standard BOD test commonly used in practice is BOD5, which involves five days of incubation at 20°C to obtain a final result. The notes’ 1–2 hour timeframe reflects the material’s specific context or example, not the full standard method. The other durations listed (60 minutes, 24 hours, five days) don’t align with what the notes describe.