12th class (Fsc) Chemistry unit 16 MCQs
51. The dissolved oxygen value…… indicates that water is polluted:
a. Less then 5ppm
b. Less than 4 ppm
c. Equal to 5 ppm
d. Greater then 4 ppm
52. which process is not involved to improve the qualities of raw water?
a. Dumping
b. Aeration
c. Chlorination
d. Coagulation
53. If BOD of a river is high, it means that the river is:
a. Very much polluted with organic= chemicals
b. Not polluted
c. Polluted with pesticides
d. Very much polluted with inorganic chemicals
54. Which one of the following factors is not used to determine the quality of water:
a. Biochemical oxygen demand
b. Available chlorine
c. Chemical oxygen demand
d. None of these
55. BOD means:
a. Biochemical oxygen dissolved
b. Boron oxygen deuterium
c. Biochemical oxygen demand
d. Biochemical oxygen death
56. The concentration of dissolved oxygen in water ranges from:
a. 8-10 ppm
b. 4-8 ppm
c. 6-10ppm
d. None of these
57. Higher value of COD is indicates:
a. More pollution
b. Less pollution
c. Does not indicate pollution
d. Both a and b
58. Oxidation reaction in natural water is catalyzed by:
a. Salts
b. Micro-organism
c. Organic matter
d. Both b and c
59. In water the most important oxidizing agent is dissolved:
a. Molecular hydrogen
b. Molecular oxygen
c. Carbon dioxide
d. Molecular nitrogen
60. The amount of oxygen consumed as a result of biological oxidation of dissolved organic matter in the sample is called:
a. BOD
b. DO
c. DU
d. COD
61. Which of the following is employed to improve the quality of raw water?
a. Aeration
b. Incineration
c. Reduction
d. Dehydration
62. The coagulant used for the purification of portable water is:
a. Nickel sulphate
b. Alum
c. Copper sulphate
d. Barium sulpate
63. When sea water is aerated which quality of water is improved?
a. Some organic matter and 1c ions are oxidized
b. Foul smell gases are removed
c. Dissolved molecular oxygen increase
d. All of these
64. The quality of raw water is improved when it is chlorinated because:
a. Hardness of water decreases
b. CI2 kills the pathogenic bacteria
c. Dissolved oxygen increases
d. None of these
65. Which quality of water is improved when raw water is aerated:
a. Foul smell gases are removed
b. All properties are improved
c. Dissolved molecular oxygen increases
d. None of these
66. Incineration is a process in which solid-waste is burnt at elevated temperature. following temperature:
a. 100 to 200oC
b. 900 to 1000oC
c. 800 to 900oC
d. None
67. The residual ash after incineration waste is disposed off in a landfill. which is lined with:
a. Methyl silicone
b. Portland cement
c. Stone-ware
d. Clay and plastic
68. When ground water seeps in the landfill a mixture of dissolved, suspended and microbial contaminants is formed, this mixture is called:
a. Refuse
b. Rancidity
c. Leachate
d. Incineration
69. Incineration is not a clean process because it produces toxic:
a. Solids
b. Liquids
c. Gases
d. Effluents
70. Which method is used for the disposal of solid waste:
a. Incineration
b. Landfill
c. Dumping
d. All of these
71. Which of the following is not common domestic materials which are recycled:
a. Iron
b. Paper
c. Glass
d. Plastics
72. The pH range of acid rain is:
a. 6-5.6
b. 7-6.5
c. Less then 5
d. 6.5-6
73. Peroxyacety initrate (PAN) is an irritant to human belngs and it affects:
a. Stomach
b. Eyes
c. Nose
d. Ears
74. To avoid the formation of toxic compounds with chlorine which substance is used for distnfecting water:
a. Alums
b. KMnO4
c. Chloramines
d. O3
75. A single chloride free radical can destroy how many ozone molecule:
a. 100000
b. 100
c. 10
d. 10000