NCERT Solutions Curiosity Chapter 6 .2 How to Group Materials? — Activity 6.3: Let us think

Book page 1046 Updated on2026-09-05

Q1.

Let us think what materials we can use to make a tumbler. Fill in the names of the materials in the spaces provided in Fig. 6.2.

Answer

Fig. 6.2 has four empty boxes joined to the word Tumbler. Fill them with four materials that can actually hold water:

Material	Why it works	Where you see it
Steel (metal)	Hard, does not break when dropped, does not leak, easy to wash	The everyday steel glass in almost every Indian home
Glass	Transparent, does not react with drinks, does not leak — but breaks easily	Glass tumblers used for shikanji and juice
Plastic	Light, cheap, unbreakable, does not leak	Plastic tumblers used in trains and school mid-day meals
Clay (baked)	Holds water, keeps it cool; a kulhad is also eco-friendly	The kulhad in which tea is served at railway stations

Other correct answers: brass or copper (a copper lota), silver for special occasions, and bamboo in the north-eastern states.

The rule behind all four: the material used to make a tumbler must be capable of holding water — it must not soak up water, must not leak, and must not dissolve or fall apart when wet.

Q2.

Would it be a good idea to use paper-like materials for making cooking utensils?

Answer

No, it would be a very bad idea. A cooking utensil is put directly on a flame, and paper fails on every count.

Paper burns. It catches fire long before dal or rice would cook.
Paper soaks up water and becomes soggy and weak. A wet paper vessel tears and the food spills.
Paper is soft and not strong. It cannot carry the weight of a kilogram of curry.
Paper does not carry heat well to the food.

Cooking utensils are therefore made of metals — steel, iron, aluminium, brass — because metals are hard, strong, do not burn, do not soak up water and pass heat quickly to the food. An earthen handi also works, because baked clay does not burn.

The lesson: we choose a material for an object depending on its properties and the purpose for which the object will be used. Paper is excellent for a notebook and useless for a kadhai.

Q3.

Why cannot a tumbler made of cloth be used for storing water?

Answer

Because cloth soaks up water and lets it leak out.

Cloth is made of thin threads woven together, and there are tiny gaps between the threads. Water passes straight through these gaps and drips out — exactly as shown in the picture of the girl whose cloth tumbler is leaking.
Cloth also absorbs water and becomes wet and heavy.
Cloth is soft, so a cloth tumbler cannot even stand up by itself — it collapses.

Why steel and glass do not leak: in steel, glass, plastic or baked clay the material is continuous — there are no gaps for the water to pass through — and the material is hard enough to keep its shape. That is why these are used for tumblers and cloth is not.

Check it yourself: Hold a handkerchief over an empty glass and pour a little water on it. The water goes right through and the cloth stays wet. Now do the same with a polythene sheet — not a drop passes.

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