31. From the following sanitizers which one comes under category of surface active agents?

A. Tetra phosphate
B. Teepol
C. Metaphosphate
D. None of these

32. The purest form of naturally occurring water is

A. rainwater
B. river water
C. pond water
D. well water

33. Calgon is used for the removal of

A. sodium carbonate
B. permanent hardness of water
C. potassium carbonate
D. none of these

34. The water being used in the dairy industry should contain not more than

A. 5 proteolytic and/or lipolytic organisms per ml
B. 10 proteolytic and/or lipolytic organisms per ml
C. 15 proteolytic and/or lipolytic organisms per ml
D. 20 proteolytic and/or lipolytic organisms/ml

35. The activated sludge process consists of returning a portion of the clarifier

A. effluent water entering the reactor
B. influent water coming out of the reactor
C. influent water entering the reactor
D. effluent water coming out of the reactor