Q. The widest explosive limit is of __________ , thereby making it the most explosive gas.

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

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Q. Polluted water having low BOD are most economically treated in

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Q. Tri-sodium phosphate is used in boiler water treatment to reduce

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Q. Scale formation in boiler is controlled by

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Q. Noise level heard at a distance of about 100 metres from a jet engine with after burner is about __________ decibels.

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Q. TLV of mercury in potable (drinking) water is about __________ ppm.

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Q. Which is the best and the most effective method for the removal of organic contaminant present in the polluted water in very small quantity (say < 200 mg/litre)?

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Q. Which is a secondary air pollutant ?

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Q. Suspended solid present in the waste water generated in blast furnace gas cooling and cleaning plant is removed by

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Q. Persons working in cement plants and limestone quarries are more prone to disease like

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Q. Particulates (< 1μm size) remaining suspended in air indefinitely and transported by wind currents are called

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Q. Operating principle of cyclone separator is based on the action of __________ dust particles.

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Q. Exposure to small amount of __________ results in high blood pressure & heart disease in human beings.

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Q. Maximum allowable concentration of CO₂ in air for safe working is __________ ppm (parts per million).

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Q. Tolerable limit of nitrogen oxides in air is __________ ppm.

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Q. Iron & manganese present as pollutant in water can not be removed by

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Q. In water chemical treatment plant, use of chloramines ensures

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Q. Which of the following is the common pollutant emitted from metallurgical smelters, thermal power plant and cement plants ?

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

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