Class 6 Air around us class 6 notes
Short Answer Questions
1. What is the wind? State three uses of wind.
2. Give four uses of air in our day to day life.
3. What is air? Write about the composition of air.
4. What is the importance of atmosphere?
5. Why is polluted air harmful to us?
6. Why do divers and mountaineers carry oxygen cylinders with them?
7. How do plants and animals help each other in the exchange of gases in the atmosphere?
8. What are sources of oxygen and carbon dioxide in the air?
9. What precautions should be taken to prevent air pollution?
Ans:
1. Fast moving air is called the wind. The three uses of the wind are:
(i) The Wind helps in the movement of yachts (sailing boats), parachutes, gliders and aeroplanes.
(ii) The Wind helps birds, bats and insects in flying.
(iii) The Wind helps in the dispersal of seeds and pollen of flowers of several plants.
2. (i) Air helps birds, bats and insects in flying.
(ii) Air plays an important role in the water cycle as it carries water vapour in it.
(iii) It helps in the drying of clothes.
(iv) Air helps in the dispersal of seeds and pollen of flowers of several plants.
3. Air is a colourless, odourless and tasteless gas. It consists of the following:
• Oxygen 21%
• Nitrogen 78%
• Carbon dioxide 0.03%
• Noble gases 0.97%
• Smoke particles variable
• Dust Particles
• Water vapour
4. Air is used in breathing, burning and respiration.
• Windmills use the movement of air to generate electricity, draw water from tube wells and run flour mills.
Air helps in the movement of yachts (sailing boats), parachutes, gliders and aeroplanes.
• The compressed air is used to fill the tubes of bicycles, automobiles and aeroplanes.
• These days, compressed air is used in the braking system of automobiles or trains in place of hydraulic brakes.
• Air helps birds, bats and insects in flying.
• Air plays an important role in the water cycle as it carries water vapour in it.
• It helps in the drying of clothes.
• Air helps in the dispersal of seeds and pollen of flowers of several plants.
5. Some air pollutants are poisonous. Inhaling them can increase the chances of health problems. People with heart and lung disease, older, adults and children are at greater risk of getting affected by air pollution.
6. The layer of atmosphere extends up to 300 kilometres above the earth’s surface. However, it gets thinner as you go higher and higher above the surface of the earth. Therefore, it becomes difficult to breathe at high altitudes. That is why mountaineers carry oxygen cylinders while trekking at high altitudes. Divers carry oxygen cylinders
with them as they cannot use the oxygen dissolved in water for breathing.
7. Carbon dioxide is required by green plants to manufacture their food in the presence of water and sunlight through the process of photosynthesis. During this process, oxygen is released which is taken in by animals
during the process of respiration.
8. During the process of burning another gas called carbon dioxide is formed. Carbon dioxide makes up a small percentage of air around us. All organic materials when they burn/consume oxygen they produce mainly
carbon dioxide.
9. Use buses and trains instead of cars, as they can carry a lot more people in one journey. This cuts down the amount of pollution produced. Walking or cycling whenever you can be even better, as it does not create
any pollution. It will also be good for your body, as regular exercise will keep you fit and healthy.
We can also help prevent pollution from our own homes which may contribute to acid rain and poor air quality and increases emissions of carbon dioxide in the atmosphere. Turning off lights when they are not needed and not wasting electricity will reduce the demand for energy. Less electricity will need to be produced and so less coal, oil and gas will have to be burnt in power stations, which means less air pollution and less carbon dioxide!
Pollution formed indoors can be reduced by ensuring that all gas appliances are working correctly. Good ventilation will improve indoor air quality by dispersing biological pollutants like dust mite, and other pollutants such as cigarette smoke. Most of the rubbish we throw away can be recycled, such as glass bottles and jars, steel
and aluminium cans, plastic bottles and waste paper. Recycling used materials use less energy than making new ones. Composting fruit and vegetable waste reduce the amount of rubbish buried at rubbish dumps.
Long Answer Questions
1. Why is it considered unhealthy to breathe in through the mouth?
2. Explain oxygen and carbon dioxide cycle in the atmosphere.
Ans:
1. It is unhealthy to breathe in through the mouth because the air that goes in through the mouth does not get filtered whereas when the air is taken in through the nose the nasal hairs trap the dust particles and filter
the air.
2. The oxygen of the atmosphere does not get consumed. Though oxygen is being used by all living organisms, its amount in the atmosphere remains nearly constant. It is because of the oxygen and carbon dioxide cycle that
continuously operates in the atmosphere. Humans and other animals exhale carbon dioxide. Plants take in carbon dioxide and exhale oxygen. Humans and other animals inhale oxygen and the process goes on continuously. So, the balance of carbon dioxide and oxygen in the atmosphere is maintained.
HOTS
1. Why should we breathe only through the nose and not through the mouth?
2. Explain why earthworms come out of the soil only during heavy rain?
Ans:
1. It is unhealthy to breathe in through the mouth because the air that goes in through the mouth does not get filtered whereas when the air is taken in through the nose, the nasal hairs trap the dust particles and filter the air.
2. Earthworms breathe by passing oxygen and carbon dioxide through their skin. For the oxygen to get through the skin and into the worms’ bloodstream properly, there needs to be some moisture on the skin, so the worms
produce mucus to keep them moist and slimy. Moisture in the ground keeps the mucus from drying out, so soil that’s a little wet actually helps the worms breathe easy. Even if the soil is very saturated or an earthworm is submerged in water, it can survive as long as there’s sufficient oxygen to pull in through the skin. But during
heavy rain, they cannot do so, so they come out of the soil during heavy rain.