Class 6 Science · Chapter 6

6. Materials Around Us

Answers to in-text questions, activities and Let us enhance our learning. NCERT Curiosity, Class 6 Science (CBSE).

Activities

6.1Make a list of objects you see around and the materials they are made up of (Table 6.1).

I observe	Materials they are made up of
Notebook	Paper
Pen	Plastic, metal, ink
Chair	Wood or iron
Window	Glass, wood or iron
Water bottle	Plastic or steel
School bag	Cloth, plastic

6.3What materials can we use to make a tumbler?

Glass, steel, copper, brass, plastic and clay.

These materials can hold water. A tumbler of cloth cannot be used because water seeps through it. Paper-like materials are not used for cooking utensils because they burn and get soaked.

Can a cricket ball be used to play tennis? Why are different materials used for making balls for various sports?

No. A cricket ball is hard and heavy and does not bounce enough for tennis.

Each sport needs a ball with a certain bounce, weight and hardness. So balls are made of different materials.

6.4Drop each ball from a fixed height and note the bounce (Table 6.2).

Ball	Bounce
Tennis ball	High
Cricket ball	Low
Hand exercise ball	Low

The tennis ball bounces the highest.

Are all lustrous materials metals?

No. Some materials are made shiny by polishing or by coating them with plastic or wax. They may not be metals. “All that glitters is not gold.”

6.5Feel whether the objects are hard or soft and find their materials (Table 6.3).

Object	Hard/Soft	Material(s)
Brick	Hard	Baked clay
Water bottle	Hard	Plastic or steel
Pillow	Soft	Cotton or foam, cloth
Tumbler	Hard	Steel or glass
Table	Hard	Wood
Sweater	Soft	Wool

Identify the nature of materials used by Ghulan (A), Sheeta (B), Sara (C) and Sheeta’s brother (D) in Fig. 6.5.

(A) Wall — opaque (B) Tree — opaque (C) Frosted glass — translucent (D) Glass window — transparent

Sheeta’s brother cannot see them through a closed wooden window because wood is opaque.

6.6Classify the objects as transparent, translucent or opaque (Table 6.4).

Transparent	Translucent	Opaque
Glass tumbler, window glass	Butter paper, frosted glass	Eraser, wooden board

Water is transparent. It can be made opaque by mixing a lot of mud or ink in it.

6.7Mix sugar, salt, chalk powder, sand and sawdust in water (Table 6.5).

Material	Observation
Sugar	Disappears in water
Salt	Disappears in water
Chalk powder	Does not disappear
Sand	Does not disappear
Sawdust	Does not disappear

Sugar and salt are soluble in water. Chalk powder, sand and sawdust are insoluble in water.

Do liquids like oil, vinegar and honey dissolve in water? What about gases?

Vinegar and honey mix completely with water. Oil does not mix and forms a separate layer.

Some gases, like oxygen, dissolve in water. Fish and water plants use this oxygen.

6.8Weigh three cups half-filled with water (A), sand (B) and pebbles (C). Which is heavier?

The cups with sand and pebbles are heavier than the cup with water. The cup with water is the lightest.

The heavier object has more mass.

Record your own readings from the balance.

Is air matter?

Yes. Air occupies space (it fills a balloon) and it has mass. So air is matter.

Let us play: Find the companion. Link the words that have a connection.

Iron — Lustrous, Solid
Copper — Lustrous
Glass — Transparent
Wood — Opaque
Plastic — Bottle

Let us enhance our learning

1Observe how your parents have organised various edibles in the kitchen. Can you suggest a better sorting method?

Keep grains, pulses, spices and oils in separate groups.
Store them in transparent, labelled containers.
Keep things used daily near the stove and others on higher shelves.
Keep older stock in front so that it is used first.

2Unscramble the letters (Column I) and match with their properties (Column II).

Column I	Column II
(i) TREMAT → MATTER	(b) Occupies space and has mass
(ii) ULSBELO → SOLUBLE	(d) Mixes completely in water
(iii) TNERPASNART → TRANSPARENT	(a) Objects can be seen clearly through it
(iv) ERUSTL → LUSTRE	(c) Shiny surface

3The containers used to store materials in shops and at home are usually transparent. Give your reasons.

We can see what is inside without opening the container. We can also see how much is left.

4State True [T] or False [F]. Correct the False statement(s).

(i) Wood is translucent while glass is opaque. — False. Wood is opaque while glass is transparent.

(ii) Aluminium foil has lustre while an eraser does not. — True

(iii) Sugar dissolves in water whereas sawdust does not. — True

(iv) An apple is a matter because it occupies no space and has mass. — False. An apple is matter because it occupies space and has mass.

5Which materials used to make chairs fulfil these properties the most?

(i) Hardness: iron, stone and wood.

(ii) Lightweight: plastic and bamboo.

(iii) Does not feel very cold in winters: wood, bamboo and plastic.

(iv) Can be cleaned and look new: plastic, iron (steel) and stone.

6Which materials will you choose for containers for (i) food waste, (ii) broken glass and (iii) wastepaper? What properties do you need to think of?

(i) Food waste: a plastic or metal bin with a lid. It should not absorb water and should be easy to wash.

(ii) Broken glass: a strong metal container. It should be hard so that glass cannot cut through it.

(iii) Wastepaper: a cardboard box or a cloth or plastic basket. It should be light.

Properties to think of: hardness, strength, whether it soaks water, and whether it is easy to clean.

7Air does not hinder us from seeing each other, but a wooden door does. It is because air is ____ and the wooden door is ____.

(i) transparent, opaque

8Material X is rigid and dissolves completely in water. Material Y easily changes shape when pressed and does not dissolve. What can X and Y be? Is X hard or soft? What about Y?

X can be sugar or salt crystals. X is hard because it does not change its shape when pressed.

Y can be a sponge or cotton. Y is soft because it changes its shape easily when pressed.

9(i) Who am I? Identify me on the basis of the given properties. (ii) Make your own ‘Who am I?’

(a) I have lustre. — A metal like iron, copper or gold

(b) I can be easily compressed. — Sponge or cotton

(d) You cannot see clearly through me. — Butter paper or frosted glass (translucent)

(e) I have mass and volume but you cannot see me. — Air

(ii) I am transparent. I take the shape of my container. Sugar and salt dissolve in me. Who am I? — Water

10From vinegar, honey, mustard oil, water, glucose and wheat flour, make two pairs where one is soluble in the other and two pairs where one is insoluble in the other.

Soluble pairs: glucose and water; vinegar and water (honey and water also).

Insoluble pairs: mustard oil and water; wheat flour and water.

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