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Class 7 Science: The World of Metals and Non-metals, 8 practice questions with answers

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These are 8 practice questions on the fourth chapter of the new NCERT Class 7 Science textbook, Curiosity, called The World of Metals and Non-metals. Each has a short answer and the textbook page it comes from. They cover the properties of metals, metals that are not hard solids, how much gold a long wire needs, rusting and how to prevent it, corrosion, why phosphorus is kept under water, sorting elements from other materials, and why metals can be made into foil. For materials in general, see our Class 6 Materials Around Us guide. Try each question before you read the answer.

These questions are our own, drafted with AI help. Every fact was checked against the page it cites by a test script, but no practising teacher has reviewed them yet. If you find a mistake, please tell us.

What the chapter says you need

Facts from the NCERT textbook (Curiosity, Grade 7, Chapter 4, printed pages 41 to 56):

Properties of metals

Question 1. Name the property of metals at work in each case: (a) a goldsmith draws a gold bar out into a thin chain; (b) a coppersmith beats a flat copper sheet into a bowl; (c) a pair of brass cymbals (manjira) rings when they are struck together; (d) heat from a stove spreads quickly across the whole base of an iron tawa.

Answer: (a) ductility; (b) malleability; (c) sonority; (d) conduction of heat. (a) Being drawn into wires is ductility. (b) Being beaten into sheets and shapes without breaking is malleability. (c) Giving a ringing sound is sonority: metals are sonorous, unlike wood or coal, which sound dull. (d) Heat passing through a material from one point to another is conduction, and metals are good conductors of heat, which is why cooking vessels are made of metal. (Malleability, page 43; ductility, page 44; sonority, page 46; conduction of heat, page 47.)

Question 2. A classmate says, "All metals are hard solids." Using the chapter, give two examples that show this is not true.

Answer: sodium and potassium are soft, and mercury is a liquid. Most metals are hard, but sodium and potassium are soft enough to be cut with a knife, and mercury is a liquid at room temperature (it has been used in thermometers). (Metals that are not hard solids, page 43.)

Question 3. The chapter says that one gram of gold can be drawn into a wire about 2 kilometres long. At that rate, how much gold would be needed for a wire 7 kilometres long? Which property does this show?

Answer: about 3.5 grams; ductility. Each gram gives about 2 km, so 7 km needs 7 ÷ 2 = 3.5 g of gold. Being drawn into wires is ductility, and gold is extremely ductile. (Ductility, page 44.)

Rusting and corrosion

Question 4. Three iron objects stand outdoors through the monsoon: a painted iron gate, a bucket coated with a layer of zinc, and a bare iron chain. (a) Which is most likely to rust, and why? (b) How are the other two protected?

Answer: (a) the bare chain; (b) by paint, and by a zinc coating (galvanisation). (a) Iron rusts when it is in contact with both air and water, that is, with moist air. The bare chain is exposed to both. (b) Rusting can be prevented by painting, oiling or greasing, and by putting a protective layer of zinc on the iron, which is called galvanisation. The gate and the bucket are protected in these ways. (Rusting and its prevention, page 50.)

Question 5. A friend says, "Only iron gets damaged by being left in the open air." (a) Is that right? (b) What is the general name for this kind of damage, and how is rusting related to it?

Answer: (a) no; (b) corrosion; rusting is the corrosion of iron. (a) Many metals change when left in the open; the chapter's examples are a green coating on copper and a black coating on silver. (b) The gradual damage of metal surfaces by air, water or other substances is called corrosion. Rusting is the corrosion of iron by moist air, which forms a brown deposit called rust. (Rusting and corrosion, page 50.)

Metals, non-metals and elements

Question 6. Phosphorus has to be stored under water, while sulfur can be kept in an ordinary jar. (a) What does the chapter say about each of them that explains this? (b) Are phosphorus and sulfur metals or non-metals?

Answer: (a) phosphorus catches fire in air, so water keeps air away from it; sulfur does not react with water and needs no such care; (b) both are non-metals. (a) Phosphorus catches fire when it is exposed to the air, so it is kept under water, which keeps the air away from it. When sulfur is put in water, nothing happens: it does not react. (That sulfur is safe to keep in an ordinary jar is our conclusion; the chapter does not discuss storing it.) (b) Both behave differently from metals with air and water, and both are non-metals. (Sulfur, phosphorus and non-metals, page 53.)

Question 7. Sort these into metals, non-metals and materials that are neither: copper, plastic, oxygen, glass, carbon, aluminium, rubber, iodine.

Answer: metals: copper and aluminium; non-metals: oxygen, carbon and iodine; neither: plastic, glass and rubber. Copper and aluminium are metals. Oxygen and carbon are named in the chapter among the non-metals, and iodine is called a non-metal where the chapter mentions its use as an antiseptic. Plastic, glass, rubber, wood and paper are not elements, so they are neither metals nor non-metals: metals and non-metals are both kinds of elements. (Metals, page 43; non-metals and elements, pages 53 and 54.)

Question 8. Aluminium foil is used to wrap food, and very thin silver foil is laid on some sweets. (a) Which property of metals makes such foils possible? (b) Which two metals does the chapter name as the most malleable of all? (c) Why could a foil like this never be made from coal or sulfur?

Answer: (a) malleability; (b) gold and silver; (c) coal and sulfur are brittle: they break into pieces instead of flattening. (a) Being beaten or pressed into thin sheets without breaking is malleability, and most metals have it; the foil on sweets and the foil round food are both thin metal sheets made this way. (b) The chapter names gold and silver as the most malleable metals. (c) Coal and sulfur are non-metals. When they are beaten they do not spread into a sheet but break into pieces, so they are called brittle, and no foil can be made from them. (Malleability and metal foils, page 43; brittle coal and sulfur, page 44.)

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Sources

All opened and read on 2 November 2026. Page numbers are the printed page numbers of the textbook; printed page = PDF page + 40 for this chapter.

The facts are from the textbook pages above. The questions, answers and checks are our own. This guide is general information; follow your teacher and the textbook.

Practise with the worksheet: Metals and Non-metals, Class 7 worksheet. Printable, in English, Hindi and Marathi, with an answer key.