ANS:A - Both A and R are true and R is the correct explanation of A

Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A). Explanation:

• Assertion (A): The minimum self-cleansing velocity in the sewer, at least once a day, must be generated.
• Reason (R): If certain deposition takes place and is not removed, it obstructs free flow and causes further deposition leading to complete blocking of the sewer.

Both Assertion (A) and Reason (R) are true statements. The self-cleansing velocity in a sewer refers to the minimum velocity required to transport solids and prevent deposition within the sewer system. It is essential to generate this velocity regularly, at least once a day, to prevent the accumulation of solids and the subsequent risk of blockages. Reason (R) correctly explains the consequence of not maintaining the minimum self-cleansing velocity. If deposition occurs and is not removed, it can obstruct free flow within the sewer. Additionally, this obstruction can lead to further deposition, as solids accumulate behind the initial blockage, eventually causing complete blockage of the sewer. However, while Reason (R) provides a valid consequence of not maintaining the minimum self-cleansing velocity, it does not directly explain why it is necessary to generate this velocity at least once a day. The frequency of generating the minimum self-cleansing velocity may depend on various factors, such as the flow characteristics of the sewer, the nature of the wastewater, and the design of the sewer system. Therefore, both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A).