Environmental Engineering

171.Ringelmann chart No. 2 corresponds to _________ percent black smoke.

1. 10
2. 20
3. 40
4. 80

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172.Salt content in sea water is about _________ percent.

1. 0.5
2. 1
3. 3.5
4. 9.05

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173.Scale formation in boiler is controlled by

1. Preheating of feed water
2. Reduction in hardness, silica&alumina in feed water
3. Keeping the pH value of feed water just below 7
4. Eliminating H2S in feed water

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174.Septic tanks are used for the _________ of the deposited solids.

1. Separation
2. Anaerobic decomposition
3. Aerobic decomposition
4. None of these

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175.Shouting by a man at his full voice corresponds to a voice level of about _________ decibels.

1. 25
2. 50
3. 80
4. 120

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176.Siderosis is a disease caused by the inhalation of _________ dust.

1. Coal
2. Silica
3. Iron
4. None of these

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177.Smog is

1. Nothing but black smoke
2. A combination of smoke and fog
3. A liquid particle resulting from vapor condensation
4. A solid particle e.g. fly-ash

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178.Smoke is produced due to

1. Insufficient supply of combustion air and insufficient time for combustion
2. Poor quality of fuel and improper mixing of fuel&combustion air
3. Poor design&overloading of furnace
4. All (A), (B) and (C)

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179.Soluble silica present in boiler feed water can be removed by

1. Coagulation
2. Filtration
3. Anion exchanger
4. Preheating it

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180.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

1. Poor visibility due to sky darkening
2. Irritation in eyes
3. Respiratory trouble
4. All (A), (B) and (C)

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