Environmental Engineering

221.Threshold limit value (TLV) of CO in air is _________ ppm.

1. 5
2. 50
3. 2000
4. 5000

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222.TLV of aldrin in public water supply system is about _________ μg/litre.

1. 0.5
2. 17
3. 357
4. 1097

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223.TLV of ammonia, nitrogen dioxide and phenol vapor in air is _________ ppm.

1. 5
2. 100
3. 1000
4. 2000

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224.TLV of lead for public sewer/waste water is about _________ ppm.

1. 1
2. 25
3. 150
4. 650

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225.TLV of mercury in potable (drinking) water is about _________ ppm.

1. 0.001
2. 0.1
3. 1
4. 5

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226.TLV of NO2&NO exposure for the human being is 5&25 ppm respectively. Prolonged exposure of human being to NO2 causes

1. Skin disorder
2. Bronchitis
3. Bone disease
4. Cancer

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227.TLV of ozone (O3) and phosgene (COCl2) in air is _________ ppm.

1. 0.1
2. 25
3. 100
4. 1000

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228.Tolerable limit of nitrogen oxides in air is _________ ppm.

1. 0.1
2. 1
3. 5
4. 25

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

1. Turbidity
2. Caustic embrittlement
3. Suspended silica
4. Dissolved oxygen

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230.Turbidity of water is an indication of the presence of

1. Suspended inorganic matter
2. Dissolved solids
3. Floating solids
4. Dissolved gases

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