Yes, air is matter — because it satisfies both tests. Air occupies space. Push an inverted empty glass into a bucket of water: the water cannot rise inside, because air is already occupying that space. A blown-up balloon or a pumped cycle tube gets bigger for the same reason. Air has mass. Weigh a deflated football and weigh it again after pumping it hard — the second reading is a little more. The extra mass is the air you pumped in. We cannot see air, but seeing is not one of the tests. Anything that occupies space and has mass is matter , whether or not our eyes can catch it. Why we cannot see it: air is a mixture of gases, and gases are transparent — light passes straight through without being scattered, exactly as it does through clean glass. We notice air only when it moves, as wind.

NCERT Solutions Curiosity Chapter 6 .4 What is Matter? — In-text Questions and Think it over!

Book page 1166 Updated on2026-09-05

Q1.

Is air matter?

Answer

Yes, air is matter — because it satisfies both tests.

Air occupies space. Push an inverted empty glass into a bucket of water: the water cannot rise inside, because air is already occupying that space. A blown-up balloon or a pumped cycle tube gets bigger for the same reason.
Air has mass. Weigh a deflated football and weigh it again after pumping it hard — the second reading is a little more. The extra mass is the air you pumped in.

We cannot see air, but seeing is not one of the tests. Anything that occupies space and has mass is matter, whether or not our eyes can catch it.

Why we cannot see it: air is a mixture of gases, and gases are transparent — light passes straight through without being scattered, exactly as it does through clean glass. We notice air only when it moves, as wind.

Q2.

Can all the materials around us be considered as different examples of matter? Discuss with your friends.

Answer

Yes. Apply the two tests to anything you like and it passes:

Thing	Does it occupy space?	Does it have mass?	Matter?
Water in a tumbler	Yes — it fills the tumbler	Yes — a full bucket is heavy	Yes
Sand and pebbles	Yes	Yes	Yes
The paper cup	Yes	Yes — the balance shows it	Yes
Air	Yes — it fills a balloon	Yes — a pumped ball is heavier	Yes
Your own body	Yes	Yes	Yes

So materials are types of matter used in the creation or making of objects. Every material around us — wood, glass, plastic, clay, metal, cloth, water, air — is an example of matter.

The wider lesson of this chapter: we grouped materials on the basis of similarities or differences in their properties, and grouping helps us study and observe patterns. Humans have classified not only things but also rocks, plants and animals — you met the classification of the living world in the chapter ‘Diversity in the Living World’. The non-living world is classified in exactly the same spirit: on the basis of properties.

Did you know? Ancient India had such a system too. Ayurveda describes all physical matter using 20 guṇa — ten pairs of opposite properties: guru (heavy) – laghu (light), hima (cold) – uṣhṇa (hot), mṛidu (soft) – kaṭhina (hard), sāndra (solid) – drava (liquid), and so on. Notice that heavy/light and soft/hard are properties you have used in this very chapter.

Q3.

Think it over! Can you think about what changes the invention of plastic brought to humans? Is it a boon or a bane?

Answer

Plastic is both — a boon in how it is used and a bane in how it is thrown away. Discuss both sides before deciding.

Plastic as a boon	Plastic as a bane
Light, unbreakable and cheap — buckets, chairs, bottles, mugs reached every home	It does not rot. A carry bag thrown today may still be lying in the soil after hundreds of years
Water-proof — pipes, tanks and packaging keep food and medicines clean and dry	Drains and nalas get choked with bags, causing floods in the rains
Saved trees, animals and metal ores — plastic replaced wood, ivory, leather and metal in many things	Cows eat discarded bags and die; fish and turtles swallow plastic in rivers and the sea
Made possible syringes, drip bottles, spectacle lenses, computers, cables, helmets and safe vehicles	Burning plastic releases poisonous smoke; tiny pieces now reach our food and water

A reasoned position: plastic itself is a very useful material — the problem is single-use plastic and careless disposal. The sensible answer is not to hate plastic but to reduce, reuse and recycle it: carry a cloth bag to the market, refuse plastic straws and cutlery, keep a steel bottle instead of buying packaged water, and hand clean plastic to the recycler instead of burning it or throwing it in a drain.

Try This: Count the plastic items thrown out of your house in one week. Mark which of them could have been replaced by cloth, steel, paper or glass. That list is your family’s plan for the next week.

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