Environmental Engineering

71.High concentration of carcinogenic hydrocarbon pollutants in atmospheric air causes

1. Cancer
2. Silicosis
3. Respiratory disease (e.g., asthma)
4. Reduced crop yield

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72.High noise level in a chemical plant can be controlled by the

1. Suppression of noise at the source itself
2. Path control of noise
3. Protection of operating personnel
4. All (A), (B)&(C)

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73.High noise levels produced during operation of fans and compressors can be reduced by using

1. Mufflers (silencers)
2. Acoustic absorbent
3. Lagging of noisy duct
4. None of these

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74.Higher concentration of CO₂ in atmosphere

1. Allows visible solar radiation (ultraviolet) of short wave-length to pass through
2. Reflects and absorbs the longer wavelength (infra-red) radiations
3. Prevents solar heat being radiated out completely, resulting in 'heat trap' i.e., global warming
4. All (A), (B) and (C)

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75.Higher concentration of nitrogen dioxide in atmospheric air causes

1. Cancer
2. Bronchitis
3. Asphyxiation
4. Corrosion

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76.Hydrogen ion concentration in distilled water is

1. 44022
2. 7 × 10-7
3. 107
4. 7 × 107

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77.In a sedimentation tank, the detention period for water ranges from _________ hours.

1. 2 to 4
2. 8 to 12
3. 16 to 20
4. 24 to 32

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78.In large thermal power stations very fine particulates present in flue gas are removed by

1. Wet scrubber
2. Bag filter
3. Electrostatic precipitators
4. Dust catcher

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79.In sewage treatment, its sedimentation is speeded up by commonly adding

1. Hydrochloric acid
2. Lime
3. Copper sulphate
4. Sodium sulphate

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80.In sewage treatment, the detention period allowed for oxidation ponds ranges from _________ weeks.

1. 1 to 2
2. 4 to 5
3. 9 to 10
4. 15 to 20

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