Q. The pH value of oxidised sewage is about

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Q. Threshold limit value (TLV) means maximum permissible/acceptable concentration. TLV of phosgene in air is about __________ ppm (parts per million).

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Q. The density of the gases (present in air) decreases with increasing altitude to such an extent, that about 70% of the mass of atmospheric air is found in the lower 5 km. of the atmosphere. This lower region of atmosphere is called the

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Q. Biological oxidation ponds remove organic matters present in the polluted water by

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Q. Which of the following is an adsorbant for removal of nitrogen oxides from gas/air ?

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Q. Out of the following, TLV of __________ is the minimum (about 0.02 ppm).

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Q. Fluorosis is caused due to the presence of excessive amount of __________ in drinking water.

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Q. Presence of nitrogen and phosphorous in waste water discharged into lakes and ponds causes

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Q. Pick out the wrong statement.

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Q. The pH value of potable water should be between

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Q. Maximum permissible limit of mercury in human blood is __________ micrograms/100 c.c.

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Q. The average thickness of ozone layer in stratosphere is about __________ dobson unit (DU).

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Q. Polyvinyl chloride containers are not suitable for storing

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Q. Presence of nitrogen in high concentration in contaminated air reduces partial pressure of oxygen in lungs, thereby causing asphyxia (suffocation) leading to death from oxygen deficiency. Concentration of N₂ in contaminated air at which it acts as a natural asphyxant is ≥ __________ percent.

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Q. TLV of ammonia, nitrogen dioxide and phenol vapor in air is __________ ppm.

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Q. Corrosion in boilers can be prevented by

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Q. Water filtration rate in a slow sand filter ranges from __________ litres/m²/hr.

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Q. Lagoons used for purification of polluted water

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Q. The principal gas evolved from sludge digestion tank is

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Q. There are thirteen metals which are treated as pollutants. Which of the following metals is not a pollutant ?

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