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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Q. The function of skimming tank in sewage treatment is to remove __________ substances.

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Q. Sooty and sulphurous smog formed due to combustion of fossil fuels particularly in winter, continues throughout the day and night. When the moist atmospheric air's water vapor condenses on the solid particles of smoke thereby forming smog (smoke + fog), it causes

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

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Q. Exposure to SO₂ containing chimney gases results in the

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Q. The detrimental effect on organism and water quality with temperature rise of aquatic system is the reduction of __________ of water.

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