Air Around Us Class 6 Extra Questions and Answers Free PDF Download
FAQs on CBSE Important Questions for Class 6 Science Air Around Us - 2025-26
1. What are the main components of air? As an important question for the exam, list them with their approximate percentages.
Air is a mixture of several gases. For the CBSE Class 6 exams, the most important components to remember are:
- Nitrogen (N₂): Makes up about 78% of the air.
- Oxygen (O₂): Constitutes about 21% of the air.
- Carbon Dioxide (CO₂): Accounts for a very small fraction, about 0.03-0.04%.
- Argon and other inert gases: Comprise about 0.9%.
- Water Vapour, Dust, and Smoke: Present in variable amounts depending on location and weather.
2. How can you demonstrate with an experiment that air is necessary for burning? This is a frequently asked activity-based question.
To prove that air, specifically its component oxygen, is essential for burning, you can perform the following steps:
- Place two small candles on a flat surface and light them.
- Cover one of the burning candles with an inverted glass tumbler.
- Observe both candles. The uncovered candle will continue to burn.
- The candle under the glass tumbler will burn for a short while and then extinguish.
This happens because the supply of air (oxygen) inside the tumbler gets used up, proving that air is necessary for combustion.
3. Explain why mountaineers carry oxygen cylinders when they climb to very high altitudes.
Mountaineers carry oxygen cylinders because as one goes to higher altitudes, the atmosphere becomes thinner. This means the amount of available air, and therefore oxygen, decreases significantly. The human body is not adapted to function with such low levels of oxygen. To avoid breathing problems and to be able to respire normally, they must carry a supplementary supply of oxygen.
4. How is the balance between oxygen and carbon dioxide maintained in the atmosphere? Explain this critical concept.
The balance between oxygen and carbon dioxide in the atmosphere is a crucial natural cycle maintained by two key processes:
- Respiration: All living organisms, including plants and animals, take in oxygen and release carbon dioxide during respiration.
- Photosynthesis: Green plants use carbon dioxide from the atmosphere, along with sunlight and water, to make their food. In this process, they release oxygen as a by-product.
This interdependence, where animals consume oxygen and produce carbon dioxide, and plants consume carbon dioxide and produce oxygen, ensures that the levels of these gases remain relatively stable in the atmosphere.
5. Describe a simple activity to show that air occupies space.
To show that air occupies space, you can do the following:
- Take a beaker or a wide-mouthed container and fill it with water.
- Take an empty, open glass bottle and hold it upside down (inverted).
- Push the inverted bottle straight down into the water-filled beaker. You will notice that water does not enter the bottle.
- Now, slightly tilt the bottle. You will see bubbles of air coming out, and water will start to fill the space that the air was occupying.
This experiment shows that the bottle was not really 'empty' but was filled with air, which prevented water from entering until the air was allowed to escape.
6. How do aquatic plants and animals get the oxygen they need to survive underwater?
Aquatic plants and animals survive by using the oxygen that is dissolved in water. Air, including oxygen, can dissolve in water. Animals living in water, like fish, use specialised organs such as gills to extract this dissolved oxygen for respiration. Similarly, aquatic plants also exchange gases through their surfaces directly with the water.
7. What are two important uses of windmills that are expected to be known for the Class 6 exam?
Windmills utilise the power of wind, which is moving air. Two important uses are:
- Generating Electricity: The rotation of the windmill blades can be used to turn a turbine, which in turn generates electricity.
- Pumping Water: Windmills have traditionally been used to draw water from wells or tube wells. The rotational motion powers a pump to lift the water to the surface.
8. Why does a lump of cotton wool shrink when it is soaked in water? Explain the reason.
A lump of cotton wool is fluffy because it has a lot of air trapped between its fine fibres. When the cotton wool is soaked in water, the water displaces this trapped air and fills the empty spaces. The layers of cotton fibres get stuck together due to the water, causing the overall volume to decrease. This makes the lump of cotton wool shrink and feel heavy.
