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4. The oxidizing chemical in the COD test is a. Mercuric sulfate b. Potassium dichromate c. Sulfuric acid plus silver sulfate 5. COD test measures a. Biodegradable organics b. Non-biodegradable organics c. Both a & b 6. For a normal domestic wastewater a. CODCOD c. COD>BOD

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In the field of environmental testing, the Chemical Oxygen Demand (COD) test is a crucial analysis used to determine the organic content in a sample. Let's explore each question with short explanations:

Question 4:

The oxidizing chemical used in the COD test is:

b. Potassium dichromate

Explanation: Potassium dichromate is a powerful oxidizing agent employed in the COD test to oxidize organic compounds present in the sample, converting them into carbon dioxide and water.

Question 5:

The COD test measures:

c. Both a & b (Biodegradable organics and Non-biodegradable organics)

Explanation: The COD test measures both biodegradable and non-biodegradable organic substances. It provides valuable information about the total organic load in the sample, including substances that can be broken down by microorganisms (biodegradable) and those that resist decomposition (non-biodegradable).

Question 6:

For a normal domestic wastewater sample:

a. COD < BOD (Chemical Oxygen Demand is typically lower than Biochemical Oxygen Demand)

Explanation: In normal domestic wastewater, the COD value is generally lower than the Biochemical Oxygen Demand (BOD) value. This indicates that the majority of organic matter in domestic wastewater is biodegradable, and the BOD test provides a more accurate representation of the organic pollution's impact on the receiving water body.

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