NCERT Solutions Curiosity Chapter 6 .3.1 Observe and identify appearance of materials — In-text Questions

Book page 1066 Updated on2026-09-05

Q1.

Discuss in class other properties of sports balls, such as size, colour, texture and how high they bounce and understand why balls are made up of specific materials for specific sports.

Answer

Here is a ready comparison to run the class discussion on.

Ball	Size	Colour	Texture	Bounce
Cricket ball	Small (about 7 cm across)	Red or white	Smooth leather with a raised seam	Low
Tennis ball	Small (about 6.5 cm)	Bright fluorescent yellow	Furry cloth cover	High
Football	Large (about 22 cm)	Usually white with black patches	Smooth stitched panels	Medium–high
Hand exercise ball	Fits in the palm	Bright single colour	Soft, slightly grippy	Medium

What the discussion should bring out:

Colour is chosen so the ball can be seen. Tennis balls are fluorescent yellow because they move very fast; a white cricket ball is used for day–night matches because a red one disappears under floodlights.
Texture decides grip and swing. The furry cover of a tennis ball lets the racquet strings bite it and give spin; the raised seam of a cricket ball is what a bowler uses to swing it.
Size and mass are matched to the body part that strikes the ball — a small hard ball for a wooden bat, a big light ball for a bare foot or head.

The one sentence to remember: a ball is made of a particular material because the properties of that material — hardness, mass, springiness, surface — are exactly what that sport needs.

Q2.

Observe Fig. 6.4 and group the objects in as many different ways as possible.

Answer

Fig. 6.4 shows 16 solid shapes. Look carefully and you will find they are a perfect set: 4 shapes × 4 colours.

Grouping 1 — by shape (4 groups of 4):

Shape	Colours in which it appears	How many
Cone	pink, orange, purple, blue	4
Square pyramid	orange, blue, pink, purple	4
Cube	blue, purple, orange, pink	4
Triangular prism	purple, pink, blue, orange	4

Grouping 2 — by colour (4 groups of 4): pink — 4 objects; orange — 4 objects; blue — 4 objects; purple — 4 objects.

Grouping 3 — by the kind of faces:

Objects with a curved surface — the 4 cones.
Objects with only flat faces — the 4 cubes, 4 pyramids and 4 prisms (12 objects).

Grouping 4 — by whether the shape comes to a point: pointed at the top — cones and pyramids (8); no point — cubes and prisms (8).

Why several answers are all correct: you might have grouped these objects according to their shape, their colour, or the material they are made of — and each grouping is complete and correct. We classify materials on the basis of their properties, and each property gives its own set of groups.

Q3.

Take a look at the pieces you have collected. Do any of these materials shine when light falls on them?

Answer

Yes — some do and some do not, and that is exactly what the sorting challenge is meant to show. Collect small pieces of paper, cardboard, wood, chalk, copper wire, aluminium foil and anything made of brass, bronze or steel, and hold each one in sunlight.

Piece	Does it shine?	Texture	Group
Copper wire	Yes	Smooth	Lustrous
Aluminium foil	Yes	Smooth, slippery	Lustrous
Brass / bronze / steel article	Yes	Smooth	Lustrous
Paper	No	Smooth but dull	Non-lustrous
Cardboard	No	Rough	Non-lustrous
Wood (unpolished)	No	Rough, with grain lines	Non-lustrous
Chalk	No	Rough, powdery	Non-lustrous

Materials that typically have shiny surfaces are said to have a lustrous appearance, and such materials are usually metals — iron, copper, zinc, aluminium, gold. Materials without a shiny surface are non-lustrous — paper, wood, rubber, jute.

Why the similarity matters: freshly cut wood looks nothing like iron, and iron looks different from copper or aluminium — yet iron, copper and aluminium share the shine that separates all three of them from wood. That shared property is what puts them into one group, the metals.

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