Assertion (A) : Flocs are masses of bacteria associated with fungal filaments in secondary treatment of sewage.
Reason (R) : Flocs help in digestion of solid waste by anaerobic respiration.
Assertion (A) : Flocs are masses of bacteria associated with fungal filaments in secondary treatment of sewage.
Reason (R) : Flocs help in digestion of solid waste by anaerobic respiration.
Show Hint
- Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation for Assertion (A).
- Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation for Assertion (A).
- Assertion (A) is true, but Reason (R) is false.
- Assertion (A) is false, but Reason (R) is true.
The Correct Option is C
Solution and Explanation
In secondary (biological) treatment the primary effluent is passed into large aeration tanks. Air is pumped in continuously.
The aeration lets useful aerobic microbes grow rapidly and form flocs.
Step 2: Check the Assertion:
Flocs are masses of bacteria held together by slime and fungal filaments, forming mesh-like structures.
This is exactly the NCERT definition. So Assertion (A) is TRUE.
Step 3: Check the Reason:
These microbes consume the organic matter in the effluent and break it down. This lowers the BOD (biochemical oxygen demand).
This happens in the presence of oxygen, so it is aerobic respiration. Anaerobic digestion happens later, in the sludge digesters.
So the statement that flocs help in digestion of solid waste by anaerobic respiration is FALSE.
Step 4: Choose the code:
A is true and R is false. This is code (C), the third option.
Option (A) needs R to be true. Option (B) needs R to be true. Option (D) says A is false. All three are wrong.
Final Answer:
Assertion is true, Reason is false, so the answer is option (C).
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↓
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