NCERT Solutions Class 8 Science
The NCERT Solutions in English Language for Class 8 Science Chapter – 4 (Materials : Metals and Non-Metals) has been provided here to help the students in solving the questions from this exercise.
Chapter – 4 (Materials : Metals and Non-Metals)
1. Which of the following can be beaten into thin sheets?
(a) Zinc
(b) Phosphorus
(c) Sulphur
(d) Oxygen
Answer – (a) Zinc
2. Which of the following statements is correct?
(a) All metals are ductile.
(b) All non-metals are ductile.
(c) Generally, metals are ductile.
(d) Some non-metals are ductile.
Answer – (c) Generally, metals are ductile.
3. Fill in the blanks.
(a) Phosphorus is a very _________non-metal.
(b) Metals are _________ conductors of heat and ____________ .
(c) Iron is ____________reactive than copper.
(d) Metals react with acids to produce ____________ gas.
Answer –
(a) Phosphorus is a very reactive non-metal.
(b) Metals are good conductors of heat and electricity.
(c) Iron is more reactive than copper.
(d) Metals react with acids to produce hydrogen gas.
4. Mark ‘T’ if the statement is true and ‘F’ if it is false.
(a) Generally, non-metals react with acids. ( )
(b) Sodium is a very reactive metal. ( )
(c) Copper displaces zinc from zinc sulphate solution. ( )
(d) Coal can be drawn into wires. ( )
Answer –
(a) Generally, non-metals react with acids. (False)
(b) Sodium is a very reactive metal. (True)
(c) Copper displaces zinc from zinc sulphate solution. (False)
(d) Coal can be drawn into wires. (False)
5. Some properties are listed in the following table. Distinguish between metals and non-metals on the basis of these properties.
| Properties | Metals | Non-metals |
| 1. Appearance | ||
| 2. Hardness | ||
| 3. Malleability | ||
| 4. Ductility | ||
| 5. Heat Conduction | ||
| 6. Conduction of Electricity |
Answer –
| Properties | Metals | Non-metals |
| 1. Appearance | Lustrous | Dull |
| 2. Hardness | Hard | Soft |
| 3. Malleability | Have property of Malleability | Do not have a property of Malleability |
| 4. Ductility | Have property of Ductility | Do not have the property of Ductility |
| 5. Heat Conduction | Good conductor of Heat | Bad Conductor of Heat |
| 6. Conduction of Electricity | Good conductor of Electricity | The bad conductor of Electricity |
6. Give reasons for the following.
(a) Aluminium foils are used to wrap food items.
(b) Immersion rods for heating liquids are made up of metallic substances.
(c) Copper cannot displace zinc from its salt solution.
(d) Sodium and potassium are stored in kerosene
Answer –
(a) Aluminium foils are used to wrap food items because aluminium metal is malleable. Therefore, it can be beaten into thin foils.
(b) Metals are good conductors of heat and electricity. Therefore, immersion rods for heating liquids are made of metallic substances.
(c) Copper cannot displace zinc from its salt solution because zinc is more reactive than copper.
(d) Sodium and potassium are stored in kerosene because they are highly reactive elements. They can easily catch fire even when in contact with air.
7. Can you store lemon pickle in an aluminium utensil? Explain.
Answer – Lemon pickle cannot be stored in aluminium utensils because lemon pickle contains acids, which can react with aluminium (metal) liberating hydrogen gas. This can lead to the spoiling of the pickle.
8. Match the substances given in Column A with their uses given in Column B.
| A | B |
| (i) Gold | (a) Thermometers |
| (ii) Iron | (b) Electric wire |
| (iii) Aluminium | (c) Wrapping food |
| (iv) Carbon | (d) Jewellery |
| (v) Copper | (e) Machinery |
| (vi) Mercury | (f) Fuel |
Answer –
| A | B |
| (i) Gold | (d) Jewellery |
| (ii) Iron | (e) Machinery |
| (iii) Aluminium | (c) Wrapping food |
| (iv) Carbon | (f) Fuel |
| (v) Copper | (b) Electric wire |
| (vi) Mercury | (a) Thermometers |
9. What happens when
(a) Dilute sulphuric acid is poured on a copper plate?
(b) Iron nails are placed in a copper sulphate solution?
Write word equations of the reactions involved.
Answer –
(a) Copper sulphate is formed and hydrogen gas is released.
Copper + Dilute Sulphuric Acid → Copper sulphate + Hydrogen (gas)
Cu + H2SO4 (conc.) → CuSO4 + H2
(b) Brown coating is deposited on the iron nails. This is because of the displacement of copper from copper sulphate solution by iron.
Iron + Copper sulphate (solution) → Iron sulphate (solution) + Copper
Fe + CuSO4 → FeSO4 + Cu
10. Saloni took a piece of burning charcoal and collected the gas evolved in a test tube.
(a) How will she find the nature of the gas?
(b) Write down word equations of all the reactions taking place in this process.
Answer –
(a) Saloni needs to add some water in the test tube in which the gas is collected. She needs to cover the tube and shake it well. Now she will test the solution with both red and blue litmus. Blue litmus turns to red which shows that the gas is acidic in nature.
(b) Charcoal reacts with oxygen to form carbon dioxide gas.
C + O2 ⟶ CO2
Carbon dioxide gas reacts with water to form carbonic acid which is acidic in nature and turns blue litmus red.
11. One day Reeta went to a jeweller’s shop with her mother. Her mother gave old gold jewellery to the goldsmith to polish. Next day when they brought the jewellery back, they found that there was a slight loss in its weight. Can you suggest a reason for the loss in weight?
Answer – Gold is metal it is washed in acidic solution. Some gold dissolve in acid to form oxide. This causes the loss of gold in the form of gold oxide. In this process certain amount of gold is lost to the acidic solution.
