Air
Class 6 Science · Chapter 11: Nature's Treasures · NCERT Curiosity section 11.1
Learn
Ira's grandmother says, "Nature gives us treasures for free: air, water, sunlight, forests, soil." These useful things from nature are called natural resources. Let's start with the one we use every second: air.
Air is a mixture of gases. About 78% is nitrogen and 21% is oxygen; the remaining 1% includes carbon dioxide, water vapour and other gases, plus dust and smoke.
We and animals breathe in oxygen; plants use carbon dioxide to make food and give out oxygen. Moving air (wind) turns windmills, dries clothes, carries seeds and helps birds glide.
Smoke from vehicles, factories and burning waste makes air polluted, which can cause breathing problems. Planting trees, using public transport and not burning garbage keep our air clean.
Explore: keep the air clean.
- Sort each action.
Remember
- Natural resources are useful things we get from nature.
- Air is a mixture: about 78% nitrogen, 21% oxygen and small amounts of other gases.
Quick check
About how much of the air is oxygen?
- 21%
- 78%
- 50%
- 1%
Answer
21%. Air is about 78% nitrogen and 21% oxygen.
Think about it
How could you show that air is present inside an 'empty' bottle?
One answer
Push the bottle mouth-down into a bucket of water and tilt it: bubbles of air escape. Or fit a balloon over its mouth and dip the bottle in hot water: the air inside expands and blows up the balloon a little.
Practice
Practise with fresh questions at three levels (easy, medium, hard), some answered hands-on, with hints and worked answers. Get 4 of your last 5 right to finish the topic.