NCERT Solutions for Class 8 Science
Chapter 4 Metals and Nonmetals
LearnFatafat offers free NCERT Solutions for Class 8 Science Chapter 4 Materials: Metals and Non-Metals. Chapter covers the topics like physical properties of metals and non metals, chemical properties of metals and non metals, uses of metals, uses of non metals and more. Check video lessons and MCQ quizzes for Class 8 Science Chapter 4 Materials: Metals and Non-Metals click here to buy.
NCERT Solutions for Class 8 Science Chapter 4 Metals and Nonmetals
1. Which of the following can be beaten into thin sheets – (a) Zinc (b) Phosphorus (c) Sulphur (d) Oxygen
Answer: 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: Generally metals are ductile. Metals are ductile suggests that metals can be drawn into wires. However, mercury is the only metal that is in liquid state and it cannot be drawn into wire.
3. Fill in the blanks.
(a) Phosphorus is a very non-metal.
Answer: reactive
(b) Metals are conductors of heat and .
Answer: electricity
(c) Iron is reactive than copper.
Answer: more
(d) Metals react with acids to produce gas.
Answer: hydrogen
4. Mark ‘T’ if the statement is true and ‘F’ if it is false.
(a) Generally, non-metals react with acids.
Answer: False (F)
(b) Sodium is a very reactive metal.
Answer: True (T)
(c) Copper displaces zinc from zinc sulphate solution.
Answer: False (F)
(d) Coal can be drawn into wires.
Answer: False (F)
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 | Are lustrous | Are dull |
| 2. Hardness | Are hard | Are brittle |
| 3. Malleability | Are malleable | Not malleable |
| 4. Ductility | Are ductile | Not ductile |
| 5. Heat Conduction | Conduct heat | Do not conduct heat |
| 6. Conduction of Electricity | Conduct electricity | Do not conduct electricity |
6. Give reasons for the following.
(a) Aluminium foils are used to wrap food items.
Answer: Aluminium metal is malleable therefore it can be beaten into thin sheets. Therefore aluminium foil is used to wrap food items.
(b) Immersion rods for heating liquids are made up of metallic substances.
Answer: Immersion rods for heating liquids are made of metallic substances because, metals are good conductor of heat and electricity.
(c) Copper cannot displace zinc from its salt solution.
Answer: Zinc is more reactive than copper. We know that, a metal can displace less reactive metal from its salt solution. Since zinc is more reactive than copper, copper cannot displace zinc from its salt solution.
(d) Sodium and potassium are stored in kerosene.
Answer: Sodium and potassium are highly reactive metals. When they come in contact with air, they can easily catch fire. Thus, sodium and potassium are stored in kerosene.
7. Can you store lemon pickle in an aluminium utensil? Explain.
Answer: Lemon pickle contains acid. Also, we know that aluminium is a metal. If lemon pickle is stored in aluminium container, then it is possible that acid from the pickle will react with aluminium metal releasing hydrogen gas. Thus, pickle will get spoiled.
8. Match the substances given in Column A with their uses given in Column B.
| Column I | Column II |
|---|---|
| (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:
| Column I | Column II |
|---|---|
| (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 copper sulphate solution? Write word equations of the reactions involved.
Answer:
a) Dilute sulphuric acid when poured on copper plate, reacts with copper metal in plate and releases hydrogen gas.
Cu (Copper) + H2SO4 (Sulphuric Acid) ⟶ CuSO4 (Copper Sulphate) + H2 (Hydrogen gas)
b) If iron nail is placed in copper solution, then iron displaces copper from copper sulphate solution. If observed carefully, the blue color of copper solution disappear and copper gets deposited over iron nail. This reaction can be given as follows-
Fe (Iron) + CuSO4 (Copper Sulphate) ⟶ FeSO4 (Iron Sulphate) + Cu (Copper)
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) Take a test tube containing gas, add few drops of water and shake it well so that gas should mix with water. Now, test the solution with litmus paper. If you observe carefully, solution turns blue litmus red, therefore, gas is acidic in nature.
b) Charcoal reacts with oxygen while burning and releases carbon dioxide gas
C ( Carbon in charcoal ) + O2 ( Oxygen ) ⟶ CO2 ( Carbon Dioxide )
Carbon dioxide reacts with water forming carbonic acid
CO2 ( Carbon Dioxide ) + H2O (Water) ⟶ H2CO3 (Carbonic Acid)
Carbonic Acid turns blue litmus red showing acidic nature of solution.
11. One day Reeta went to a jeweller’s shop with her mother. Her mother gave an 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: For polishing ornaments are dipped in aquaregia, a liquid which is mixture of hydrochloric acid and nitric acid. When ornaments are dipped in this liquid upper layer of gold dissolves and inner shiney layer appears on top. Thus, weight reduction is found in jewellery after polishing.
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Chapter 4 – Metals and Nonmetals