Topic outline

    • Pollution of Air and Water

      Q33. Describe the threat to the beauty of the Taj Mahal.

      Ans. The beauty of the Taj Mahal in white marble is being threatened by air pollution in the area surrounding the Taj. Due to increase in pollutants like sulphur dioxide and nitrogen dioxide in air, acid rain take place. Acid rain corrodes the marble of the monument. The phenomenon is also called “Marble cancer”. Suspended particulate matter, such as the soot particles emitted by Mathura oil refinery, has contributed towards yellowing of the marble.


      Q34. What are the different ways in which water gets contaminated?

      Ans. Following are the different ways in which water gets contaminated:

                                i.        Many industries discharge harmful chemicals into rivers and streams, causing the pollution of water.

                               ii.        Pesticides and weedicides used for the protection of crops get dissolve in water and are washed into water bodies from the fields. They also seep into the ground to pollute ground water.

                              iii.        Sometimes untreated sewage is thrown directly into rivers which pollute the river water.

      Q35. At an individual level, how can you help reduce air pollution?

      Ans. An individual can reduce air pollution by:

                                i.        By using public transport or car pool as far as possible.

                               ii.        By not using vehicles for short distances.

                              iii.        By using clean fuels such as LPG and CNG instead of diesel and petrol.

                              iv.        By disposing the garbage properly.

                               v.        By controlling the emissions from vehicles and household chimneys.

                             vi.        By planting trees in the surroundings.

               vii.        By saying no to crackers.


      Q36. How water can be made safe for drinking?

      Ans. Water can be made safe for drinking in the following ways:

                               i.        Filtration is one of the effective ways of purifying water. A popular household filter is a candle type filter.

                              ii.        Water can be made safe for drinking by boiling. Boiling kills the germs present in the water.

                             iii.        Chlorination is a commonly used chemical method for purifying water. It is done by adding chlorine tablets or bleaching powder to the water.

      Q37. How can we prevent wastage of water? (Any 4 points)

      Ans. We can prevent wastage of water in the following ways:

                                i.        Reuse water for washing and for other household tasks. For example, water used for washing vegetables may be used to water plants in the garden.

                              ii.        Turn off the tap immediately after use.

                             iii.        Get the leaking taps repaired immediately.

                             iv.        Brush teeth by filling water in a mug.


      Q38. What are the harmful effects of global warming?

      Ans. Harmful effects of global warming

                               i.        Global warming can cause sea levels to rise dramatically. In many places, coastal areas have already been flooded.

                              ii.        Global warming could result in wide ranging effects on rainfall patterns, agriculture, forests, plants and animals.

                             iii.        There has to be check on the emission of greenhouse gases at the present level. Otherwise, the temperature may rise by more than 2 degrees Celsius by the end of the century which is very dangerous.

      Q39. Explain circumstances leading to acid rain. How does acid rain affect us?


      What is acid rain? How is acid rain caused? What are the harmful effects of acid rain?

      Ans. Harmful gases such as sulphur dioxide and nitrogen dioxide react with the water vapour present in the atmosphere to form sulphuric acid and nitric acid. The acids drop down with rain, making the rain acidic. This is called acid rain.

      Effects of acid rain

                               i.        It corrodes the statues, buildings and historical monuments and damages them.

                              ii.        It damages crops.

                             iii.        It kills aquatic animals such as fish.

      Q40. You are a member of the municipal body of your town.

      Make a list of measures that would help your town to ensure the supply of clean water to all its residents.

      Ans. To ensure the supply of clean water to all its residents the following steps must be taken:

                               i.        The main water source must be built in clean surrounding and should be maintained properly.

                              ii.        Water should be treated properly to make it free from harmful germs, chemicals and impurities.

                             iii.        Chemical methods such as chlorination must be used for purifying water.

                             iv.        The area around water pipes must also be clean.


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