Chapter -10

ENVIRONMENTAL POLLUTION

BACK EXERCISE QUESTION

Question 1: How have humans emerged as the greatest threat to the environment?

Answer 1: Humans have carried out various activities to suit their needs. These have caused changes in the environment. In doing so, the humans have become the greatest threat to the environment.

Question 2: What causes air pollution? How is air pollution harmful?

Answer 2: Air pollution is caused by both human made and natural factors. Some human made factors are smoke from factories, vehicles, burning of fuels and firecrackers. Sandstorms, volcanic eruptions, forest fires and pollen from plants and flowers are some natural causes of air pollution.

Polluted air is harmful and can affect our health. Breathing polluted air can cause diseases. Air pollution is also harmful for plants. Plants do not get enough nutrients because of air pollution. This slows down their growth, they become weak and eventually they die.

Question 3: What is water pollution? How do water bodies get polluted?

Answer 3: When harmful substances are released into water bodies they cause water pollution. Water bodies get polluted when

1. Chemical waste from factories are dumped in them.

2. Household waste and untreated sewage are dumped in them.

3. People bathe and wash clothes in rivers and lakes.

4. Leakage from oil tankers.

Natural factors such as storms also cause water pollution. Storms cause soil and other particles to dissolve in water. This pollutes the water and it cannot be used for drinking and cooking.

Question 4: Write a short note on soil pollution.

Answer 4: When harmful substances are released into the soil, it causes soil pollution. Soil is also polluted when harmful substances get accumulated in it. Main causes of soil pollution are solid wastes such as garbage, refuse from forest and Agriculture, and refuse from mines. Soil becomes in fertile because of pollution. It also harms the organisms living in the soil.

Question 5: List some causes of noise pollution. How does noise pollution harm us?

Answer 5: Noise pollution is caused by horns of vehicles, loudspeakers and loud music, firecrackers, washing machines, vacuum cleaners, air conditioners and mixer grinders.

Noise pollution is harmful to all living things. It causes stress, irritation and loss of hearing.

Think and answer

Question: Which is more environment-friendly – a bicycle or a car? Why?

Answer: Bicycle is more environmentally friendly as it does not cause pollution.