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Environmental Chemistry Test - 47

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Environmental Chemistry Test - 47
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Weekly Quiz Competition
  • Question 1
    1 / -0
    Maximum ozone depletion is caused by
    Solution
    The primary cause for ozone depletion are CFCs. CFCs or Chlorofluorocarbons are the compounds that contain carbon and hydrogen along with chlorine and fluorine. They are used as refrigerants and in air conditioners. CFCs release chlorine radicals that react with ozone and cause its degradation. The mechanism of ozone depletion by CFC is as follows:
                  UV- C
    CFCl3 ----------------> CFCl2 + Cl
                   UV-C
    CFCl2 -----------------> CFCl + Cl
    Cl + O3 ----------------> ClO + O2
    ClO + O3 --------------> Cl + 2O2
    Hence, CFC causes degradation of ozone. Also, the chlorine atom remains in the atmosphere and reacts with another molecule of ozone.
    So, the correct answer is 'CFC'.
  • Question 2
    1 / -0
    The term acid rain was given by
    Solution

    The term acid rain was coined in 1872 by Robert Angus Smith. The acid rain is contains water having pH around 5.6. When the air pollutants like oxides of nitrogen and oxides of sulphur reach the troposphere, they react with the water or moisture and forms acids like nitric acid, nitrous acid or sulphuric acid. These acids then precipitate with the rain to form the acid rain. Hence, the correct answer is 'Angus'.

  • Question 3
    1 / -0
    Damage of Taj Mahal is being caused by
    Solution
    Taj Mahal is situated in Agra which has a number of industries. The pollutants from industries are released in the air which include oxides of sulphur and nitrogen. The oxides of sulphur and nitrogen react with water vapours in the atmosphere and form sulphuric acid and nitric acid which come down on earth in the form of rain and this is known as acid rain. 
    The acid rain reacts with the marble of Taj Mahal which is made up of calcium carbonate and this has resulted in the change of colour of marble of Taj Mahal from white to pale yellow. Thus acid rain due to industrialization in Agra is damaging the Taj Mahal.
    So, the correct answer is 'Acid rain'.
  • Question 4
    1 / -0
    UV radiations cause
    Solution
    UV radiation causes formation of pyrimidine dimers in DNA due to which two bases (thymine) get joined by covalent linkage to form a dimer. These dimers can lead to mutations as during replication, these dimers are skipped. However, certain enzymes are there which repair the damaged DNA.
    So, the correct answer is 'Formation of thymine dimers'.

  • Question 5
    1 / -0
    Freon gas causing stratosphere $$O_3$$ depletion is mainly released from
    Solution
    Freon gas is a type of chlorofluorocarbon (CFC) i.e., it contains carbon and hydrogen along with fluorine and chlorine. It is used as a refrigerant. CFCs release chlorine atoms in the atmosphere that react with ozone and cause its depletion. Hence, Freon causes ozone depletion and it is released from refrigerators.
    So, the correct answer is 'Refrigerators'.
  • Question 6
    1 / -0
    $$O_3$$ in ozone layer is formed by action of
    Solution
    Ozone molecule (O3) is formed in the stratosphere in presence of UV radiations.
    The first step is the breaking of an oxygen molecule into two oxygen atoms by UV radiation:
                                                   UV
                                 $$O_2$$  ---------------> $$O$$ + $$O$$
    The Oxygen atoms then combine with oxygen molecule to form a molecule of ozone:
                                $$O_2$$ + $$O$$ -----------------> $$O_3$$
    So, the correct answer is 'UV radiation'.
  • Question 7
    1 / -0
    Which is more hazardous to human health?
    Solution
    A. Pyrethrum is the crude extract obtained from the flowers of Chrysanthemum plant.
    B. Dichlorodiphenyltrichloroethane or DDT is a crystalline, colourless and odourless compound which is used as an insecticide. DDT on runoff from the fields reach the water bodies and gets accumulated in the bodies of fishes. When fishes are eaten by birds, it gets accumulated in the body of birds and hence, in this way it gets incorporated in the food chain. It gets deposited in the fatty tissues of animals as it is fat soluble and cause serious health hazards.
    C. Rotenone is  a colourless and odourless crystalline compound used as a broad spectrum pesticide and insecticide. 
    D. Humulin is the genetically engineered insulin hormones of humans.
    Hence, DDT is more hazardous to human health.
    So, the correct answer is 'DDT'.
  • Question 8
    1 / -0
    Nitrogen oxides released in the stratosphere cause ozone depletion due to
    Solution
    Nitrogen oxide which causes ozone depletion is Nitrous oxide. It is similar to CFCs in that it is stable when it is released in the troposphere but when it reaches stratosphere, it releases ozone depleting substances which react with ozone and cause its degradation through nitrogen-oxide catalysed reaction.
    So, the correct answer is 'Reacting with ozone'. 
  • Question 9
    1 / -0
    Smog that occurs mainly due to automobile exhausts and still air is
    Solution
    The photochemical reaction is caused by absorption of energy in the form of light. The word smog is formed of smoke and smog. Photochemical smog is the major contributor to the air pollution and is composed of primary and secondary pollutants. Primary pollutants being the nitrogen oxides and volatile organic compounds like Unsaturated hydrocarbons that have double or triple covalent bonds between adjacent carbon atoms. e.g., Ethylene. Gasoline and natural gas are major source of unsaturated hydrocarbon. Butadiene, benzene are some hydrocarbons that are lethal to human health and have potential to cause cancer.
    Hence, the correct answer is 'Photochemical smog'
  • Question 10
    1 / -0
    Most harmful pesticide is
    Solution
    A. 2,4-D or 2,4-dichlorophenoxyacetic acid is a herbicide used to kill weeds.
    B. 2,4,5-T or 2,4,5-trichlorophenoxyacetic acid is a synthetic auxin, also used as a herbicide.
    C. Dichlorodiphenyltrichloroethane or DDT is most commonly used insecticide.
    D. PAN or peroxyacetyl nitrate is a secondary pollutant which is present in photochemical smog.
    Most harmful pesticide is DDT because it is nonbiodegradable and on runoff from the fields , it reaches the water bodies and gets accumulated in the bodies of fishes. When fishes are eaten by birds, it gets accumulated in the body of birds and hence, in this way it enters the food chain. With each successive trophic level, concentration of DDT increases and this is known as biomagnification. 
    So, the correct answer is 'DDT'.
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