91.Inhalation of silica dust causes a disease called
Bronchitis
Silicosis
Pneumoconiosis
None of these
Correct answer: (B) Silicosis
92.Inorganic impurities causing water pollution is
Fats
Carbohydrates
Salts of metals
Protein
Correct answer: (C) Salts of metals
93.Insufficient washing of sand grains in a rapid sand filter causes
Air binding
Shrinkage of filtering media
Mud balls
Expansion of filtering media
Correct answer: (C) Mud balls
94.Ionisation potential employed in the industrial electrostatic precipitator is of the order of
30 to 70 kV DC
30 to 70 kV AC
230 V AC
230 V DC
Correct answer: (A) 30 to 70 kV DC
95.Iron&manganese present as pollutant in water cannot be removed by
Ion exchange process
Oxidation followed by settling&filtration
Lime soda process or manganese zeolite process
Chlorination
Correct answer: (D) Chlorination
96.Iron&manganese present in the polluted water is removed by
Simple filtration
Oxidation followed by settling&filtration
Chemical coagulation
Chlorination only
Correct answer: (B) Oxidation followed by settling&filtration
97.Irradiation of water by ultraviolet light of suitable wavelength is commonly used for disinfection of water in
Food industry
Municipal sewage treatment
Petroleum refinery
Iron&steel plant
Correct answer: (A) Food industry
98.Lagooning process is mainly a means of the
Sludge disposal
Reduction of excessive flow in sewers
Biological treatment of wastes
None of these
Correct answer: (A) Sludge disposal
99.Lagoons used for purification of polluted water
Are large shallow artificial lakes also known as clarification lakes, maturation ponds or oxidation ponds
Use micro-organisms/bacteria in presence of dissolved oxygen
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
All (A), (B)&(C)
Correct answer: (D) All (A), (B)&(C)
100.Lead exhausted in the atmosphere by automobiles using leaded petrol (i.e. tetraethyl lead for improving octane number) is a lethal air pollutant which causes