Environmental Engineering

21.Aerobic biological oxidation ponds used for the purification of polluted water

1. Destroys/removes pathogen from the sewage
2. Is not very effective for non-biodegradable substances (e.g. ABS) containing effluents
3. Destroys/removes pathogen much more effectively if the sewage is chlorinated
4. All (A), (B)&(C)

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22.Aerodynamic noise resulting from turbulent gas flow is the most prevalent source of valve noise in fluid flow control. It is caused due to

1. Reynold stresses
2. Shear forces
3. Both (A)&(B)
4. Neither (A) nor (B)

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23.Aerosols present in atmospheric air may be

1. Positively charged
2. Negatively charged
3. Neutral
4. Combination of all (A), (B)&(C)

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24.Arsenic pollutant is not generated in _________ industries.

1. Tanneries
2. Glass&ceramic
3. Beverages
4. Any of these

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25.As per the world health organisation (WHO) specification, the maximum permissible concentration (i.e., TLV) of particulate matter in air is _________ μg/m3.(μg-microgram)

1. 10
2. 90
3. 800
4. 750

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26.Atmospheric pollution caused by the exhaust gas of supersonic transport air-crafts is mostly in the atmospheric region called

1. Thermosphere
2. Stratosphere
3. Troposphere
4. Mesosphere

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27.Automobile exhaust is passed through two compartments catalytic converter employing platinum as catalyst for

1. Conversion of CO into CO₂ in the second compartment
2. Conversion of NOx into N₂ and NH₃ in the first compartment
3. Oxidation of unburnt hydrocarbon fuel in the second compartment
4. All (A), (B) and (C)

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28.Bacterial aerobic oxidation of polluted water in biological oxidation ponds is done to purify it. Presence of bacteria helps in

1. Coagulation and flocculation of colloids
2. Oxidation of carbonaceous matter to CO₂
3. Nitrification or oxidation of ammonia derived from breakdown of nitrogenous organic matter to the nitrite and eventually to the nitrate
4. All (A), (B) and (C)

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29.Bag filter design is predominantly dependent on gas temperature, as it affects the gas density&viscosity and the selection of filtering material. The pressure drop in a bag filter is

1. Inversely proportional to viscosity of gas
2. Proportional to the viscosity&density of the gas
3. Proportional to the pressure of the gas
4. Both (B) and (C)

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30.Beyond what concentration of H2S in air, acute danger to human life exists?

1. 50 ppm
2. 100 ppm
3. 300 ppm
4. 700 ppm

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