Threshold limit value (TLV) of CO in air is _____________ ppm?
Threshold limit value (TLV) of CO in air is _____________ ppm?
A. 5
B. 50
C. 2000
D. 5000
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Main pollutant present in automobile exhaust is_________________?
Main pollutant present in automobile exhaust is_________________?A. CO
B. CO2
C. NO
D. Hydrocarbons____________ substances present in sewage are removed in grit chamber during sewage treatment?
____________ substances present in sewage are removed in grit chamber during sewage treatment?A. Organic
B. Fatty
C. Inorganic
D. DissolvedIn sewage treatment, the detention period allowed for oxidation ponds ranges from _____________ weeks?
In sewage treatment, the detention period allowed for oxidation ponds ranges from _____________ weeks?A. 1 to 2
B. 4 to 5
C. 9 to 10
D. 15 to 20Infective bacteria in water is killed by the _____________ process?
Infective bacteria in water is killed by the _____________ process?A. Sterilisation
B. Aeration
C. Disinfection
D. None of theseLagoons used for purification of polluted water_______________?
Lagoons used for purification of polluted water_______________?A. Are large shallow artificial lakes also known as clarification lakes, maturation ponds or
oxidation ponds
B. Use micro-organisms/bacteria in presence of dissolved oxygen
C. Gives an excellent final effluent (with 3 to 4 lagoons arranged in series) having suspended
solid < 1 mg/litre and BOD = 3.8 mg/litre
D. All A., B. & C.Most of the atmospheric air pollutants are present in large quantity in__________________?
Most of the atmospheric air pollutants are present in large quantity in__________________?A. Stratosphere
B. Thermosphere
C. Troposphere
D. Mesosphere