Q. When the concentration of SO₂ in air is greater than __________ ppm, it gives a pungent smell.

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Q. Presence of a certain minimum quantity of flourine is desirable in potable water to prevent

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Q. Death may occur, when SO₂ concentration in atmospheric air exceeds __________ ppm.

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Q. Which of the following acts as a natural source of air pollution ?

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Q. Higher concentration of CO₂ in atmosphere

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Q. Permissible safe limit (TLV) of __________ toxic gas is 100-1000 parts per million (ppm).

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Q. Radioactive substances present in the polluted water stream can be removed by

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Q. Most of the bacteria in sewage are

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Q. Which of the following is the most major constituents of air pollutants ?

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Q. Shouting by a man at his full voice corresponds to a voice level of about __________ decibels.

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Q. Carbonaceous particles having size less than 1 μm are called

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Q. __________ substances present in sewage are removed in grit chamber during sewage treatment.

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Q. Pick out the wrong statement pertaining to 'green house' for the plants.

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Q. In water treatment, alum[Al₂(SO₄)₃] is used for the process of

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Q. Pick out the one which is not a chemical coagulant.

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Q. Presence of iron and manganese in water causes

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Q. Septic tanks are used for the __________ of the deposited solids.

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Q. The term Biological Oxygen Demand (BOD) is used in relation to

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Q. The destruction of water-borne pathogens is termed as disinfection of water. Which of the following is a water disinfectant ?

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Q. Disinfection of water is done to destroy pathogenic bacteria and thus prevent water-borne diseases. Disinfection of water may be done by the use of

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