Correct Answer : Centrifugal pumps
Explanation : Centrifugal pumps produce a head and a flow by increasing the velocity of the liquid with the help of the rotating vane impeller. Centrifugal pumps include radial, axial and mixed flow units.
Correct Answer : Option (B) : Eutrophication
Explanation : Eutrophication is the growth of huge amounts of algae and other aquatic plants leading to the deterioration of water quality. The untreated wastewater is rich in organic matter which demands oxygen.
Correct Answer : Option (C) : 20°C
Correct Answer : Option (D) : All of the above