In very first stage of decomposition of the organic matter in sewage A. Nitrites are formed B. Nitrates are formed C. Carbondioxide is formed D. Ammonia is formed

The correct answer is D. Ammonia is formed.

In the very first stage of decomposition of the organic matter in sewage, ammonia is formed. This is because the organic matter is broken down by bacteria into ammonia and other simpler compounds. The ammonia is then released into the environment, where it can be harmful to plants and animals.

Nitrites and nitrates are formed later in the decomposition process, when the ammonia is converted by bacteria into these compounds. Carbon dioxide is also formed during decomposition, but it is not formed in the very first stage.

Here is a more detailed explanation of each option:

• Option A: Nitrites are formed. This is not the correct answer because nitrites are formed later in the decomposition process, when the ammonia is converted by bacteria into these compounds.
• Option B: Nitrates are formed. This is not the correct answer because nitrates are formed later in the decomposition process, when the ammonia is converted by bacteria into these compounds.
• Option C: Carbondioxide is formed. This is not the correct answer because carbon dioxide is formed during decomposition, but it is not formed in the very first stage.
• Option D: Ammonia is formed. This is the correct answer because ammonia is formed in the very first stage of decomposition of the organic matter in sewage.