Environmental Engineering in CE
Presence of nitrogen in high concentration in contaminated air reduces partial pressure of oxygen in lungs, thereby causing asphyxia (suffocation) leading to death from oxygen deficiency. Concentration of N₂ in contaminated air at which it acts as a natural asphyxant is ≥ __________ percent.

84
92
88
80

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Environmental Engineering in CE
Bacterial aerobic oxidation of polluted water in biological oxidation ponds is done to purify it. Presence of bacteria helps in

Nitrification or oxidation of ammonia derived from breakdown of nitrogeneous organic matter to the nitrite and eventually to the nitrate
Oxidation of carbonaceous matter to CO₂
Coagulation and flocculation of colloids
All of these

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Environmental Engineering in CE
Smoke is produced due to

Poor quality of fuel and improper mixing of fuel & combustion air
Poor design & overloading of furnace
Insufficient supply of combustion air and insufficient time for combustion
All of these

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