In domestic water sewage, which of the following things is not a part of 'Dissolved materials'?

Correct option is D

Ans. (d) Sand
Sol.Sand is a suspended particle, not a dissolved substance. Dissolved materials include nitrates, phosphates, and calcium ions, which are found in solution.
Explanation of each option:
· (a) Nitrate – Dissolved salt in sewage.
· (b) Phosphate – Common dissolved fertilizer runoff.
· (c) Calcium – Dissolved mineral in hard water.
· (d) Sand – Correct. Suspended solid, not dissolved.