Environmental Issues Test

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Environmental Issues Test - 29

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Weekly Quiz Competition

Question 1
1 / -0

'Biological Oxygen Demand' (BOD) is a measure of

A
Industrial wastes poured into water bodies

B
Extent to which water is polluted with organic compounds

C
Amount of carbon monoxide inseparably combined with haemoglobin

D
Amount of oxygen needed by green plants during night

Solution

Biochemical oxygen demand is a measure of how much dissolved oxygen is being consumed as microbes break down organic matter. A high demand, therefore, can indicate that levels of dissolved oxygen are falling, with potentially dangerous implications for the river's biodiversity. High biochemical oxygen demand can be caused by high levels of organic pollution, caused usually by poorly treated wastewater; high nitrate levels, which trigger high plant growth.
Question 2
1 / -0

Measuring 'Biochemical Oxygen Demand' (BOD) is a method used for

A
Estimating the amount of organic matter in sewage water.

B
Measuring the activity of Saccharomyces cervisae in producing curd on a commercial scale.

C
Working out the efficiency of RBCs, about their capacity to carry oxygen.

D
Working out the efficiency of oil driven automobile engines.

Solution

Biochemical oxygen demand (BOD) is the amount of oxygen, expressed in mg/L or parts per million (ppm), that bacteria take from water, when they oxidize organic matter.
Bacteria in water live and multiply when organic matter is available for food and oxygen is available for oxidation. About one-third of the food bacteria consumed becomes the solid organic cell material of the organisms. The other two-thirds is oxidized to carbon dioxide and water by the biochemical action of the bacteria on the oxygen dissolved in the water. Micro-organisms involved in biodegradation of organic matter in the receiving water body consume a lot of oxygen, and as a result there is a sharp decline in dissolved oxygen downstream from the point of sewage discharge. This causes mortality of fish and other aquatic creatures.
Question 3
1 / -0

The presence of ozone in the atmosphere of earth

A
Hinders higher rate of photosynthesis

B
Has been responsible for increasing the average global temperature in the recent past

C
Helps in checking the ultra violet rays to earth

D
Is advantageous, since it supplies oxygen for people travelling in jets

Solution

Ultraviolet radiations are highly energetic radiations which may cause harmful mutagenic changes. The stratosphere present in the atmosphere contains ultraviolet radiation absorbs the harmful ultraviolet radiation and protects us from several chronic diseases. Only ozone effectively absorbs the most energetic ultraviolet light, known as UV-C and UV-B, which causes biological damage. The protective role of the ozone layer in the upper atmosphere is so vital that scientists believe life on land probably would not have evolved - and could not exist today - without it.
Thus, the correct answer is option C.
Question 4
1 / -0

Supersonic jets cause pollution by thinning of

A
O$$_3$$ layer

B
SO$$_2$$ layer

C
O$$_2$$ layer

D
CO$$_2$$ layer

Solution

90% of naturally occurring atmospheric ozone occurs in the stratosphere. Stratospheric ozone is very important, it removes almost all incoming UVA, and 70% of the incoming UVB at equator, 90% at poles. All aircraft produce water, CO$$_2$$, CO etc. in exhaust gases. Most commercial flights are confined to the troposphere, but high-level supersonic aircraft inject pollutants into the stratosphere, which leads to the thinning of the ozone layer. Of these nitrogen oxides are especially harmful.
Thus, the correct answer is option A.
Question 5
1 / -0

If the river water is polluted with domestic sewage and garbage, it leads to the depletion of

A
CO$$_2$$

B
CO

C
O$$_2$$

D
All of the above

Solution

A lake rich in domestic sewage and garbage nutrients will leads to eutrophication. Eutrophication is when the environment becomes enriched with nutrients. This can be a problem in aquatic habitats such as lakes as it can cause algal blooms and other aquatic plants. Following this, overcrowding occurs and plants compete for sunlight, space and oxygen. It deoxygenate the water enough to kill the fish and other animals. Thus, the correct answer is option C.
Question 6
1 / -0

Global warming can be controlled by

A
Reducing reforestation, increasing the use of fossil fuel

B
Increasing deforestation, slowing down the growth of human population

C
Increasing deforestation, reducing efficiency of energy usage

D
Reducing deforestation, cutting down use of fossil fuel
Solution
- Global warming is the biggest challenge for the developing countries like India. The rapid increase in human population and the increased levels of pollution are the major contributors of global warming.
- The percentage of heat-trapping carbon dioxide (CO$$_2$$) increases due to the burning of fossil fuels to generate electricity, fuel our cars, and heat our homes.
- Deforestation also increases the concentration of carbon dioxide in the atmosphere.
So, the correct answer is option D.
Question 7
1 / -0

The worst enemy of ozone is

A
Liquid NH$$_3$$

B
SO$$_2$$

C
CH$$_4$$

D
CFCs

Solution

The ozone hole is thinning of an ozone layer which is present in the stratosphere region around 26-30kms above the Earth surface. The ozone hole is caused by chlorofluorocarbons (CFCs) found in air conditioners, aerosol spray cans, refrigerants etc. CFCs can not be removed in troposphere and moves in Stratosphere layer where it reacts with ozone, thereby releasing of free chlorine atoms and causes the ozone layer to deplete. It serves as a shield from the harmful ultraviolet B radiation emitted by the sun. Ozone hole becomes a cause of concern as it allows UV radiations to reach the earth surface which causes major problems like Skin cancer, reduction in the rate of photosynthesis.
So, the correct answer is option D.
Question 8
1 / -0

The major pollutants to deplete ozone are

A
Chlorofluorocarbons

B
Nitrogen oxides

C
Hydrocarbons

D
All of the above

Solution

Pollution leads to the addition of harmful components in the environment which adversely affect the quality of the environment. CFCs is an organic compound and a volatile derivative of methane, ethane, and propane. It is known as Freon. They are used as a refrigerant. The radical chlorine escapes from CFC in the presence of UV radiation and is long lived in the upper atmosphere where it catalyzes the conversion of ozone into oxygen molecule.
So, the correct answer is option A.
Question 9
1 / -0

Which method is most effective in controlling floods?

A
Digging deep canals

B
Reforestation

C
Deforestation

D
Constructing dams

Solution

Loss of vegetation (deforestation) results in an increased risk of flooding. With natural forest cover, the flood duration should decrease. Reducing the rate of deforestation should improve the incidents and severity of floods. Reforestation and afforestation are two strategies to increase the vegetation cover, that can improve infiltration and interception rates, and thus regulate flood peaks. Reforestation refers to planting trees in areas, where they have been cut down, while afforestation means planting trees, where they have never existed. Dams and reservoirs are effective in controlling floods by reducing peak flows.
Question 10
1 / -0

Ozone layer of upper atmosphere is being destroyed by

A
Sulphurdioxide

B
Carbondioxide

C
Chlorofluorocarbon

D
Smog

Solution

CFCs are used as refrigerants in refrigerators and AC. CFCs discharged in the lower part of atmosphere move upward and reach the stratosphere. In the stratosphere, UV rays act on them releasing Cl atoms. Cl reduces the ozone and releases molecular oxygen, Cl atoms are not consumed in the reaction. Hence, whatever CFCs are added to the stratosphere, they have permanent and continuing effects on ozone levels. This has resulted in the formation of a large area of thinned ozone layer, commonly called as the ozone hole.

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Re-Attempt Weekly Quiz Competition

Environmental Issues Test - 29

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Environmental Issues Test - 29

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SHARING IS CARING

Question 1

Industrial wastes poured into water bodies

Extent to which water is polluted with organic compounds

Amount of carbon monoxide inseparably combined with haemoglobin

Amount of oxygen needed by green plants during night

Solution

Question 2

Estimating the amount of organic matter in sewage water.

Measuring the activity of Saccharomyces cervisae in producing curd on a commercial scale.

Working out the efficiency of RBCs, about their capacity to carry oxygen.

Working out the efficiency of oil driven automobile engines.

Solution

Question 3

Hinders higher rate of photosynthesis

Has been responsible for increasing the average global temperature in the recent past

Helps in checking the ultra violet rays to earth

Is advantageous, since it supplies oxygen for people travelling in jets

Solution

Question 4

O$$_3$$ layer

SO$$_2$$ layer

O$$_2$$ layer

CO$$_2$$ layer

Solution

Question 5

CO$$_2$$

CO

O$$_2$$

All of the above

Solution

Question 6

Reducing reforestation, increasing the use of fossil fuel

Increasing deforestation, slowing down the growth of human population

Increasing deforestation, reducing efficiency of energy usage

Reducing deforestation, cutting down use of fossil fuel

Solution

Question 7

Liquid NH$$_3$$

SO$$_2$$

CH$$_4$$

CFCs

Solution

Question 8

Chlorofluorocarbons

Nitrogen oxides

Hydrocarbons

All of the above

Solution

Question 9

Digging deep canals

Reforestation

Deforestation

Constructing dams

Solution

Question 10

Sulphurdioxide

Carbondioxide

Chlorofluorocarbon

Smog

Solution

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