8th Class Science Pollution of Air and Water Question Bank Pollution of Air and Water

  • question_answer
    As proved by many studies greenhouse effect is rapidly increasing because of increase in concentration of carbon dioxide. In the given graph the increase in carbon dioxide concentration is shown. What could be X corresponding to it?
    (i) Rate of photosynthesis in plants
    (ii) pH of the oceans
    (iii) Water level of ocean
    (iv) Average global temperature of Earth
     

    A) (i) and (iii) only           

    B) (ii) and (iv) only          

    C) (ii) only           

    D) (iv) only

    Correct Answer: C

    Solution :

    An increase in concentration of \[\text{C}{{\text{O}}_{2}}\] gas in the atmosphere leads to an increase in greenhouse effect and therefore warmer global temperature. In consequence to global warming, the glaciers are melting and thereby sea level is rising. An estimated 34-40% of carbon dioxide released by humans into atmosphere dissolves in oceans, rivers and lakes, resulting in a decline in pH of water sources (acidification). \[\text{C}{{\text{O}}_{2}}\]reacts with water to form carbonic acid. Some of these extra carbonic acid molecules react with a water molecule to give a bicarbonate ion. \[\text{C}{{\text{O}}_{2}}\]allows plants to grow faster (more\[\text{C}{{\text{O}}_{2}}\]enhances photosynthesis).


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