Q. In sewage treatment, the detention period allowed for oxidation ponds ranges from __________ weeks.

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Q. The maximum permissible noise level to which a man working in a chemical plant can be exposed for eight hours per day is about __________ decibels.

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Q. The most commonly used chemical coagulant in water treatment is

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Q. The biological decomposition of organic substances in wastes controlled conditions is called

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Q. Lung cancer & DNA breakage are the major ill effects of excessive ozone exposure to human beings. Ozone layer depletion in the atmosphere is mainly caused by the presence of

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Q. Smog is not formed due to the presence of __________ in the atmosphere.

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Q. Pick out the correct statement.

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Q. Which of the following is not a source of ozone emission in the atmosphere ?

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Q. Oceans act as sinks for atmospheric gases including carbon dioxide whose concentration in the atmosphere is increased by the

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Q. Pick out the correct statement.

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Q. The upper layer of atmosphere is called the

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Q. Coal mines drainage waste water (acidic in nature) results from the earth's water percolating through the voids created in coal bed during mining. This polluted water which either drains out naturally to water courses or are removed before starting the mining is

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Q. Fine grit present in sewage is removed in the __________ during sewage treatment.

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Q. The lowest layer of atmosphere is known as the

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Q. 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)

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Q. Which of the following is not a weightless pollutant ?

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Q. In water treatment plant, zeolite process is used to remove the __________ of water.

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Q. For existence of aquatic life in water, the dissolved oxygen content in it, should not be less than __________ ppm.

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Q. Fresh sewage is __________ in nature.

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Q. In a sedimentation tank, the detention period for water ranges from __________ hours.

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