71.
Which one of the following statements is not true ? A
Dissolved oxygen $$(DO)$$ in cold water can reach a concentration upto $$10\,ppm.$$
B
Clean water would have a $$BOD$$ value of $$5\,ppm.$$
C
Fluoride deficiency in drinking water is harmful. Soluble fluoride is often used to bring its concentration upto $$1\,ppm.$$
D
When the $$pH$$ of rain water is higher than $$6.5,$$ it is called acid rain.
Answer :
When the $$pH$$ of rain water is higher than $$6.5,$$ it is called acid rain.
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Acid rain is the rain water containing sulphuric acid and nitric acid which are formed from the oxides of sulphur and nitrogen present in the air as pollutants and rain water has a pH range of $$4-5.$$
72.
Which of the following statements are not correct ? A
(ii) and (iv)
B
(ii) and (iii)
C
(ii), (iii) and (iv)
D
(iii) and (iv)
Answer :
(iii) and (iv)
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For statement (iii), Methemoglobinemia ( blue baby syndrome ) is caused due to excess of nitrate in drinking water.
73.
Match the column I with column II and mark the appropriate choice.
Column I
Column II
a.
Peroxyacetyl nitrate
1.
Global warming
b.
Polychlorinated biphenyls
2.
Photochemical smog
c.
Dioxides of carbon and sulphur
3.
Water pollutant
d.
IR active molecules
4.
Acid rain
A
a - 2, b - 3, c - 4, d - 1
B
a - 3, b - 4, c - 2, d - 1
C
a - 4, b - 2, c - 3, d - 1
D
a - 1, b - 3, c - 2, d - 4
Answer :
a - 2, b - 3, c - 4, d - 1
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74.
Classical smog is a common pollutant in places which have A
high altitudes
B
high temperature
C
high concentration of $$S{O_2}$$ in air
D
high concentration of $$N{H_3}$$ in air
Answer :
high concentration of $$S{O_2}$$ in air
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Classical smog is produced from gases like $$S{O_2},$$ particulates and high humidity in the atmosphere.
75.
Match the upper limit concentrations of the pollutants in drinking water given in column I with column II and mark the appropriate choice.
Column I
Column II
a.
Lead
1.
$$500\,ppm$$
b.
Sulphate
2.
$$1\,ppm$$
c.
Nitrate
3.
$$50\,ppb$$
d.
Fluoride
4.
$$50\,ppm$$
A
a - 2, b - 3, c - 1, d - 4
B
a - 3, b - 1, c - 4, d - 2
C
a - 1, b - 4, c - 3, d - 2
D
a - 4, b - 2, c - 3, d - 1
Answer :
a - 3, b - 1, c - 4, d - 2
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76.
Incomplete combustion of petrol or diesel in automobile engine produces A
$$CO\,\,{\text{and}}\,\,{H_2}O\,\,{\text{vapours}}$$
B
$$CO\,\,{\text{and}}\,\,N{O_2}$$
C
$$CO$$
D
$$S{O_2}$$
Answer :
$$CO$$
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$$CO$$ is produced as a result of incomplete combustion of fossil fuels.
77.
Presence of which of the following fuel gas in the exhaust fumes shows incomplete
combustion of fuel ? A
Sulphur dioxide
B
Carbon monoxide and water vapour
C
Carbon monoxide
D
Nitrogen dioxide
Answer :
Carbon monoxide
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Presence of $$CO$$ in the exhaust fumes shows incomplete combustion.
78.
When rain is accompanied by a thunderstorm, the collected rain water will have a $$pH$$ value A
slightly lower than that of rain water without thunderstorm.
B
slightly higher than that when the thunderstorm is not there.
C
uninfluenced by occurrence of thunderstorm.
D
which depends upon the amount of dust in air.
Answer :
slightly lower than that of rain water without thunderstorm.
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Normal rain water has $$pH\,5.6.$$ Thunderstorm results in the formation of $$NO$$ and $$HN{O_3}$$ which lowers the $$pH.$$
79.
Match the column I with column II and mark the appropriate choice.
Column I
Column II
a.
Biodegradable pollutants
1.
$$DDT$$
b.
Non-biodegradable pollutants
2.
$$S{O_2}$$
c.
Primary pollutants
3.
$$PAN$$
d.
Secondary pollutants
4.
Sewage
A
a - 3, b - 4, c - 2, d - 1
B
a - 2, b - 3, c - 4, d - 1
C
a - 1, b - 2, c - 3, d - 4
D
a - 4, b - 1, c - 2, d - 3
Answer :
a - 4, b - 1, c - 2, d - 3
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80.
Which of the following pollutants is not harmful for lungs? A
$$CO$$
B
$$C{O_2}$$
C
$$S{O_2}$$
D
$$N{O_2}$$
Answer :
$$C{O_2}$$
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