NCERT 6th Class (CBSE) Science: Air Around Us

Question: What do you mean by ‘atmosphere’?

Answer: A blanket of air surrounding the earth is called the atmosphere. It extends up to about 1000 km above the surface of the earth.

Question: Carbon dioxide is present to the extent of only 0.03% by v0lume in air. Why then is it considered to be so important?

Answer: Air contains very title carbon dioxide – only 0.03%. However, it is a very crucial component of air.

Question: What is humidity?

Answer: The amount of water vapour present in the air is known as humidity.

Question: What is the difference between breathing in and respiration?

Answer:

1. All living things breathe in oxygen.
2. Living things need energy all the time for various life process, they need to breathe in oxygen all the time.
3. The process of breathing in, getting energy from food and breathing out is called respiration.

Question: Do plants require nitrogen? Why?

Answer: Nitrogen is required by plants for their growth. But plants are not able to absorb the nitrogen directly from the air. Nitrogen in the air is brought to earth in the from of nitric acid through lightning and rain. Soil changes it to nitrate compounds which is absorbed by the plants. Also, nitrogen in the air is used by us to manufacture fertilizers.These fertilizers again provide the essential nitrogen to plants.

Question: What is the importance of the ozone layer in the atmosphere?

Answer: The upper atmosphere contains a layer of gas called ozone. It prevents harmful rays of the sun from reaching the earth. These rays, called ultraviolet rays, can cause eye problems and skin cancer.

Question: How do fish breathe?

Answer: Fish, breath in oxygen dissolved in water. Fishes have organs called gills, oxygen dissolved in the water is absorbed.

Question: Why is it considered unhealthy to breathe in through the mouth?

Answer: Dust and smoke in the air are harmful for our respiratory system. Fine hair and mucus present in our nostrils filter them out and prevent them from getting into our respiratory system. That is why it is unhealthy to breathe through our mouth.