Practice Test: Question Set - 15
1. The ratio of oxygen available to the oxygen required for stabilization of sewage is called the
- (A) Bacterial stability factor
- (B) Relative stability
- (C) Biological oxygen demand (BOD)
- (D) Oxygen ion concentration
2. Irradiation of water by ultraviolet light of suitable wavelength is commonly used for disinfection of water in
- (A) Food industry
- (B) Municipal sewage treatment
- (C) Petroleum refinery
- (D) Iron & steel plant
3. Ozone level is generally found to be depleted in India in the month of
- (A) February
- (B) July
- (C) April
- (D) December
4. Persons working in cement plants and limestone quarries are more prone to disease like
- (A) Cancer
- (B) Asthma
- (C) Silicosis
- (D) Fluorosis (bone disease)
5. Thermal pollution due to excessive heat & temperature in the working place causes
- (A) Reduction in working efficiency of manpower
- (B) Fatigue
- (C) High breathing rate
- (D) All (a), (b) & (c)
6. Presence of soluble organics in polluted water causes
- (A) Undesirable plants growth
- (B) Depletion of oxygen
- (C) Fire hazards
- (D) Explosion hazards
7. Replenishment of dissolved oxygen in water stream polluted with industrial waste occurs by
- (A) Natural aeration of water stream
- (B) Photosynthetic action of algae
- (C) Both (a) & (b)
- (D) Neither (a) nor (b)
8. Presence of iron and manganese in water causes
- (A) Reduction in its dissolved oxygen content
- (B) Discoloration of bathroom fixtures
- (C) Temporary hardness
- (D) None of these
9. The main industrial source of emission of hydrogen sulphide air pollutant is
- (A) Petroleum refineries
- (B) Coal based thermal power plants
- (C) Pulp and paper plant
- (D) Metallurgical roasting & smelting plant
10. TLV of mercury in potable (drinking) water is about __________ ppm.
- (A) 0.001
- (B) 0.1
- (C) 1
- (D) 5
11. Limestone powder is injected during pulverized coal burning in boilers to __________ the flue gases.
- (A) Reduce SO2 content in
- (B) Catalytically convert SO2 to SO3 in
- (C) Increase the dew point of
- (D) None of these
12. Bacterial aerobic oxidation of polluted water in biological oxidation ponds is done to purify it. Presence of bacteria helps in
- (A) Coagulation and flocculation of colloids
- (B) Oxidation of carbonaceous matter to CO2
- (C) Nitrification or oxidation of ammonia derived from breakdown of
nitrogenous organic matter to the nitrite and eventually to the nitrate
- (D) All (a), (b) and (c)
13. Bag filter design is predominantly dependent on gas temperature, as it affects the gas density & viscosity and the selection of filtering material. The pressure drop in a bag filter is
- (A) Inversely proportional to viscosity of gas
- (B) Proportional to the viscosity & density of the gas
- (C) Proportional to the pressure of the gas
- (D) Both (b) and (c)
14. Presence of a certain minimum quantity of fluorine is desirable in potable water to prevent
- (A) Dental cavities
- (B) Scale formation
- (C) Water-borne disease
- (D) Corrosion
15. Presence of __________ hardness is responsible for the temporary hardness in water.
- (A) Carbonate
- (B) Calcium
- (C) Chloride
- (D) Sulphate
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