Environmental Engineering

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

1. Using the activities of bacteria and other micro organisms
2. Aerobic oxidation
3. Both (A)&(B)
4. Neither (A) nor (B)

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32.Black smoke coming out of the chimney of a furnace is an indication of the use of _________ in the furnace.

1. Low amount of excess combustion air
2. Large quantity of excess combustion air
3. Hydrocarbon fuel
4. Pulverised coal as fuel

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33.BOD of raw municipal sewage may be in the range of about _________ mg/litre.

1. 43862
2. 44109
3. 150-300
4. 2000-3000

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34.Brown spots in fabrics will be caused by washing with water containing large amount of:

1. Iron
2. Zinc
3. Iodine
4. Bromine

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35.Carbon monoxide is a pollutant, which causes

1. Respiratory disease (e.g. asthma)
2. Asphyxiation (suffocation) leading to death
3. Retardation in crop growth
4. Damage to building materials like marble

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

1. Grit
2. Aggregates
3. Aerosols
4. Smoke

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37.Carcinogenic air pollutants cause

1. Bone decay
2. Cancer
3. Asphyxiation (suffocation)
4. Anemia

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38.CFC (chloro fluoro carbon) is very highly reactive in causing depletion of ozone layer in the atmosphere. Each atom of chlorine liberated from CFC is capable of decomposing _________ molecules of ozone.

1. 10²
2. 10⁵
3. 10⁹
4. 10¹⁵

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39.Coal washing waste water containing about 3% suspended solids (comprising of clay, slate, stone etc.) is treated for solid particles removal

1. By chemical coagulation
2. In sedimentation tanks equipped with mechanical scrapper
3. In vacuum filter
4. In clarifiers

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40.COD of raw municipal sewage may be in the range of about _________ mg/litre.

1. 43862
2. 44109
3. 90-120
4. 1500-2500

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