. In sewage, nitrates and phosphates are
In sewage, nitrates and phosphates are-
(a) Organic impurities.
(b) Inorganic impurities.
(c) Both of them.
(d) None of them.
Explanation: Sewage contains organic and inorganic impurities. Organic impurities include human faeces, urea, etc. while inorganic impurities include nitrates, phosphates and metals.