Question 1. What are the different ways in which water gets contaminated?
Solution 1. Following are the different ways in which water gets contaminated:
i)Industrial waste: Industries releases harmful chemicals into water sources.
ii) Sewage waste: The waste materials released from the kitchen, laundry and toilets pollute water.
iii) Agricultural chemicals: Rains and floods carry these harmful chemicals used by the farmers for enhancing crop production to water bodies, which pollutes the water bodies.
Question 2. At an individual level, how can you help reduce air pollution?
Solution 2. At an individual level we can reduce air pollution in the following ways:
i) We should avoid the usage of personal vehicles and should use public transport as much as possible.
ii) disposal of garbage should be properly done without burning it.
iii) The number of emissions from household chimneys and vehicles should be controlled.
iv) fuel, diesel and petrol used for vehicles should be replaced by LPG and CNG.
Question 3. Clear, transparent water is always fit for drinking. Comment.
Solution 3. Clear, transparent water can also carry many harmful chemicals which can cause severe diseases. So, the water should be drunk only after purifying it because even clean looking water may be contaminated.
Question 4. 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.
Solution 4.
The following are the measures taken by us to ensure the supply of clean water to our town residents:
a) proper cleaning of water tanks and water pipes.
b) the sewage line should not come in contact with the water supply pipes.
c) To purify water, chlorination should be done.
Question 5. Explain the differences between pure air and polluted air.
Solution 5. Pure air is consisting of 78% nitrogen, 21% oxygen and 0.03% carbon dioxide. Apart from these, gases like methane, argon, ozone and water vapours are also present in pure air. Whereas, the polluted air is filled with more harmful substances or gases such as Sulphur dioxide, carbon monoxide, nitrogen dioxide and particulate matter.
Question 6. Explain the circumstances leading to acid rain. How does acid rain affect us?
Solution 6. The burning of fossil fuels like diesel and coal releases harmful pollutants in the atmosphere like Sulphur dioxide and nitrogen dioxide. When these pollutants like Sulphur dioxide and nitrogen dioxide react with the water vapours present in the atmosphere, they form sulphuric acid and nitric acid respectively. These acids come down in the form of precipitation this is known as acid rain.
Effects of the acid rain:
a) It destroys crops and plants.
b) It is harmful to the building, especially to white marble buildings like the Taj Mahal.
c) it causes skin problems.
Question 7. Which of the following is not a greenhouse gas?
(a) Carbon dioxide
(b) Sulphur dioxide
(c) Methane
(d) Nitrogen
Solution
(d) Nitrogen
Question 8. Describe the ‘Green House Effect’ in your own words.
Solution 8. The greenhouse effect is the cause of global warming as it increases the earth’s temperature. When the sun’s radiations fall on the earth’s surface some of its parts get absorbed by it and the rest of the parts are reflected into space. The greenhouse gases methane, CO2 and water vapour trap these radiations and do not allow these gases to escape these gases in result increase in the earth’s temperature.
Question 9. Prepare a brief speech on global warming. You have to deliver the speech in your class.
Solution 9. The continuous increase in the earth’s temperature is called global warming. It occurs because of the increment of greenhouse gases in the atmosphere. Global warming is a threat to life because a lot of health problems occur due to global warming. To control global warming we should immediately control the pollution in our surroundings because after all, pollution is the main cause of the increased global warming as it produces harmful greenhouse gases.
Question 10. Describe the threat to the beauty of the Taj Mahal.
Solution 10. Air pollutants are discolouring the white marble of the taj mahal. Taj mahal is centre of attraction for tourists but the increasing pollution has become a matter of concern. The industries in and around Agra are the main reason for the increment of pollutants like Sulphur dioxide and nitrogen dioxide in the air. The acids drop down with the rain forming the acid rain that corrodes the marble of the building. The phenomenon is known as “marble cancer”. Pollutants emitted by the Mathura oil refinery are the main reason for the yellowing of the marble.
Question 11. Why does the increased level of nutrients in the water affect the survival of aquatic organisms?
Solution 11. The increased level of nutrients in the water leads to an increase in the population of algae in the water body. A lot of oxygen is used by the decomposers to eat the increased number of algae in the water. This will deplete the level of oxygen dissolved in the water. This in turn affects the aquatic life to die.