Environmental Engineering

41.Color test of water is done with an instrument called

1. Tintometer
2. Colorimeter
3. Electro-chemical cell
4. Turbidimeter

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42.Corrosion in boilers can be prevented by

1. Deaeration of feed water
2. Enhancing pH of feed water by adding alkali
3. Feeding sodium sulphite or hydrazine phosphate to the boilers, which combines with oxygen and prevents corrosion
4. All (A), (B) and (C)

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43.Deaeration of high pressure boiler feed water is done to reduce

1. Foaming from boilers
2. Its dissolved oxygen content
3. Its silica content
4. Caustic embrittlement

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44.Death may occur, when SO₂ concentration in atmospheric air exceeds _________ ppm.

1. 20
2. 100
3. 400
4. 200

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45.Direct reaction of unsaturated hydrocarbons with either NO or NO2 produces an eye irritating pollutant compound known as

1. Photochemical smog
2. Peroxyacetyl nitrate (PAN) or methyl nitrite
3. Benzopyrene
4. Polyacrylonitrile

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46.Disinfection of water is done to destroy pathogenic bacteria and thus prevent water-borne diseases. Disinfection of water may be done by the use of

1. Ozone and iodine
2. Chlorine or its compounds
3. Ultraviolet light for irradiation of water
4. All (A), (B)&(C)

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47.Disinfection of water is done to remove

1. Color
2. Bad taste
3. Foul odour
4. Bacteria

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48.Dissolved oxygen content in river water is around _________ ppm.

1. 5
2. 100
3. 250
4. 500

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49.During sewage treatment, the sewage is subjected to _________ treatment in Imhoff tank.

1. Filtration
2. Digestion
3. Sedimentation
4. Both (B) and (C)

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50.During which of the following operating conditions of an automobile, carbon monoxide content in the exhaust gas is maximum?

1. Idle running
2. Acceleration
3. Cruising
4. Deceleration

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