We have Provided the CBSE Solutions chapter-wise. Class 8 Science Chapter 4 Materials: Metals and Non-Metals with Answers by expert subject teacher for latest syllabus and examination. Students can take a free CBSE Solutions of Materials: Metals and Non-Metals. Each question has right answer Solved by Expert Teacher.
CBSE Solutions Class 8 Science Beehive Prose
Page No. 53
Exercise
Q1. Which of the following can be beaten into thin sheets?
(a) Zinc
(b) Phosphorus
(c) Sulphur
(d) Oxygen
Answer: (a) Zinc
Q2. 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.
Q3. 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) reactive
(b) good, electricity.
(c) more
(d) hydrogen
Q4. Mark ‘T’ if the statement is true and ‘F’ if it is false.
(a) Generally, non-metals react with acids. ( )
Answer: False
(b) Sodium is a very reactive metal. ( )
Answer: True
(c) Copper displaces zinc from zinc sulphate solution. ( )
Answer: False
(d) Coal can be drawn into wires. ( )
Answer: False
Q5. 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 2) Hardness 3) Malleability 4) Ductility 5) Heat Conduction 6) Conduction of Electricity | Lustrous Hard Can be beaten into thin sheets Can be drawn into wires Good conductors of heat Good conductors of electricity | Dull Soft Cannot be beaten into thin sheets Cannot be drawn into wires Poor conductors of heat Poor conductors of electricity |
Q6. Give reasons for the following.
(a) Aluminium foils are used to wrap food items.
Answer: Aluminium is malleable and can be drawn into thin sheets hence Aluminium foils are 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 up of metallic substances because metals are good conductors of heat and electricity.
(c) Copper cannot displace zinc from its salt solution.
Answer: Copper cannot displace zinc from its salt solution because Zinc is more reactive than copper.
(d) Sodium and potassium are stored in kerosene.
Answer: Sodium and Potassium are highly reactive metals which readily reacts with atmospheric Oxygen to catch fire hence Sodium and Potassium are stored in kerosene.
Q7. Can you store lemon pickle in an aluminium utensil? Explain.
Answer: No, we cannot store lemon pickle in an aluminium utensil because aluminium is a metal and metals readily react with acids to produce hydrogen. When aluminium comes in contact with lemon, which is acidic, would react to give hydrogen and the pickles will be spoiled.
Q8. Match the substances given in Column A with their uses given in Column B.
| A | B |
| (i) Gold (ii) Iron (iii) Aluminium (iv) Carbon (v) Copper (vi) Mercury | (a) Thermometers (b) Electric wire (c) Wrapping food (d) Jewellery (e) Machinery |
Answer:
| A | B |
| (i) Gold (ii) Iron (iii) Aluminium (iv) Carbon (v) Copper (vi) Mercury | (d) Jewellery (e) Machinery (c) Wrapping food (f) Fuel (b) Electric wire (b) Electric wire |
Q9. 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) Copper sulphate is formed and hydrogen gas is released.
Copper + dil. sulphuric acid → Copper sulphate + Hydrogen (gas)
(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
Q10. 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?
Answer: Add a few drops of water in the test tube containing gas. Now, cover the test tube and shake it well. After shaking, test the solution with blue litmus and red litmus. It will turn blue litmus red. Thus, the gas is acidic in nature.
(b) Write down word equations of all the reactions taking place in this process.
Answer: Charcoal reacts with oxygen to form carbon dioxide gas.
Q11. 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: In order to polish the gold ornament, it is to be dipped into a liquid called aqua regia (a mixture of hydrochloric acid and nitric acid). On getting dissolved in the environment of aqua regia, the outer layer of gold dissolves and an inner shiny layer appears. The dissolving of the layer causes a reduction in the weight of the jewellery.
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