Saturday , September 26 2020

NCERT 8th Class (CBSE) Science: Pollution of Water and Air

Question: Aforestation leads to both air and water conservation, as well as soil conservation. How?

Answer: Plants slow down the speed of water flowing over land and hence improve its absorption by the soil. This increases the level of groundwater. Plants absorb excess carbon dioxide and give out oxygen. So they also help in reducing air pollution. Thus Aforestation leads to both air and water conservation. Again this leads to conservation of soil as roots of plants hold the soil and prevent its erosion.

Question: Does potable water mean pure water without any impurities?

Answer: Yes, potable water means pure water without solid impurities and also without germs.

Question: What are the different ways in which water gets contaminated?

Answer: Water gets contaminated by following:

  1. Untreated sewage
  2. Practice of bathing and washing near a water body
  3. Practice of cremating the dead bodies near river banks
  4. Oil Spill

Question: At an individual level, how can you help reduce air pollution?

Answer: I can take following steps to reduce air pollution:

  1. I will walk when I have to go to the nearby market.
  2. I will use my bicycle to go to school.
  3. I will prefer to use public transport.

Question: Clear, transparent water is always fit for drinking. Comment.

Answer: Even the clear, transparent water may contain harmful germs. Thus the clear water is not necessarily fit for drinking.

Question: 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.

Answer: I will take following steps to ensure the supply of clean water:

  1. All leakages in the pipelines should be repaired.
  2. Water should be properly treated before being supplied to the households.
  3. A sewage treatment plant should be installed in the municipal area.

Question: Explain the differences between pure air and polluted air.

Answer: The difference between Pure air and Polluted air:

Pure air
Polluted air
1. All the gases are in correct ratio.
1. Harmful gases are in higher ratio.
2. No SPMs in air.
2. High level of SPMs in air.
3. Smog is absent.
3. Smog can be present.
4. It is not harmful for living beings.
4. It is harmful for living beings.

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