61. Hydrothermal reservoirs refer to:

(a) Hot water stored in a natural dam
(b) Large pools of steam or hot water trapped in porous rocks
(c) Molten rock found below earth’s crust
(d) Heat contained in shallow ground

Answer: (b)

62. The leakage of methyl isocyanate (MIC) gas from Union Carbide India Ltd, Bhopal is due to:
(a) Excess production of MIC
(b) Breakdown of MIC plant
(c) Entry of a large volume of water into MIC storage tank, causing valve to open
(d) Hole was formed on the MIC tank

Answer: (c)

63. Thermal pollution is mainly caused due to:
(a) Sudden change in temperature caused by periodic plant outages
(b) Sudden decrease in temperature of river or lake
(c) Increase of dissolved oxygen (DO) in water bodies
(d) Gradual increase in temperature of earth

Answer: (a)

64. ′Nitrogenous oxygen demand′ (NBOD) is oxygen needed to:
(a) Convert ammonia to nitrate
(b) Convert nitrogen dioxide to nitrogen trioxide
(c) Denitrifying bacteria to grow
(d) Oxidize organic matters

Answer: (a)

65. A sample of groundwater has . Its total hardness will be nearly:
(a) 2.4 meq/L
(b) 3.8 meq/L
(c) 4.4 meq/L
(d) 5.8 meq/L

Answer: (d)

66. Trickling filter is used in:
(a) Filtering fruit juice
(b) Secondary / biological treatment of wastewater
(c) Primary treatment of wastewater
(d) Tertiary treatment of wastewater

Answer: (b)

67. 

Answer: (c)

68. In ‘Fluidized Bed Combustion’ (FBC) boiler, sulfur oxides formed during combustion react with the lime-stone (CaCO3) to:
(a) Form solid CaSO4 which falls to the bottom of the furnace
(b) Form solid CaS which falls to the bottom of the furnace
(c) Separate ash from coal
(d) Increase the combustion rate

Answer: (a)

69. ‘Trash’ in Municipal Solid Waste (MSW) is:
(a) Combustible portion of rubbish
(b) Non combustible portion of rubbish
(c) Garbage residue of food
(d) Construction of auto bodies and industrial waste

Answer: (a)

70. ‘Volatile Organic Compounds’ (VOCs) are effectively removed by:
(a) Vacuum filter
(b) Air-stripping tower followed by granular activated carbon filter
(c) Plate and frame filter
(d) Sonicator

Answer: (b)