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NCERT Solutions for Class 7th Science Chapter 4 In-text Questions — Malleability

Book page 43 Updated on2026-09-19

Q1.
Analyse Table 4.1. Identify the objects that are lustrous in appearance and hard.
S.No.Object/MaterialAppearance (lustrous/non-lustrous)Hard/SoftEffect of hammering (flattens/breaks into pieces)
1.Piece of copper
2.Piece of aluminium
3.Iron nail
4.Piece of coal
5.Lump of sulfur (pea-sized)
6.Block of wood
Table 4.1: Appearance, hardness, and effect of hammering on different objects or materials (blank, as printed on page 43).
Answer

The lustrous and hard objects are the piece of copper, the piece of aluminium and the iron nail.

Lustrous + hard → copper, aluminium, iron → these are metals
Non-lustrous + not so hard → coal, sulfur, wood

The shine that copper, aluminium and iron show is given a special name — metallic lustre.

Why it happens: the surface of a metal reflects light evenly, so it gleams. Coal and sulfur scatter light in all directions, so they look dull however much you polish them.
Q2.
Are all metals hard and solid?
Answer

No. “Hard and solid” is the general rule for metals, not a law without exceptions.

  • Sodium and potassium are metals, yet they are so soft that they can be cut with a knife, like a piece of cheese.
  • Mercury is a metal that is a liquid at room temperature — you have seen it in the thermometers of the chapter ‘Temperature and its Measurement’ of Grade 6 Curiosity.
Tip: in science, learn the general property first, then learn the famous exception. For metals the two exceptions worth remembering are: softest — sodium and potassium; liquid — mercury.
Q3.
Which objects did you find become flat on beating with a hammer?
Answer

The piece of copper, the iron nail and the piece of aluminium became flat on beating.

Beaten into a thin sheet without breaking = malleability
Most metals are malleable; gold and silver are the most malleable of all.

Everyday proof of malleability is all around you — the thin silver foil (vark) on sweets and the aluminium foil used to wrap food are both metals beaten into sheets.

Q4.
Can you give some examples of metal sheets?
Answer
  • Silver vark on barfi and other sweets — silver beaten until it is thinner than paper.
  • Aluminium foil for wrapping rotis and packing food.
  • Copper sheets beaten into tawas, parats and temple roofing.
  • Galvanised iron sheets used for roofs, buckets and trunks.
  • Gold leaf used on idols and in traditional decoration.
Did you know? Gold can be beaten into a sheet so thin that light passes through it with a greenish tinge. That is malleability pushed to its limit.
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