Question: What is malleability? Give some examples of malleable metals.
Answer: Malleability is the property of metals by which they can be beaten into thin sheets without breaking. Metals like gold, silver, aluminium, and copper are malleable.
Question: Which metal is highly malleable and why is it used in jewellery?
Answer: Gold is the most malleable metal. It can be beaten into very thin sheets without breaking. Because of this property, it is easily shaped into beautiful designs, so it is widely used in making jewellery. It is also shiny and does not corrode easily.
Question: What is ductility? Name two metals that show high ductility.
Answer: Ductility is the property of a material by which it can be drawn into thin wires. Metals like gold and copper show high ductility.
Question: What is the difference between malleability and ductility?
Answer: The difference between malleability and ductility is :
|
Malleability |
Ductility |
|
Property of metals to be beaten into thin sheets. Example: Aluminium foil. |
Property of metals to be drawn into thin wires. Example: Copper wires. |
|
Shows ability to withstand compression. |
Shows ability to withstand tension. |
|
Used in making utensils and sheets. |
Used in making electrical wires. |
Question: What are metals and non-metals? Give two examples each of metals and non-metals.
Answer: Metals are elements that are generally hard, shiny, malleable and good conductors of heat and electricity.
Examples of metals: Iron, Copper.
Non-metals are usually dull, brittle and poor conductors.
Examples of non-metals: Oxygen, Sulphur.
Question: Write the differences between metals and non-metals.
Answer: The differences between metals and non-metals are :
|
Metals |
Non-metals |
|
Metals are lustrous and shiny. |
Non-metals are dull. |
|
They are good conductors of heat and electricity. |
They are poor conductors. |
|
Metals are malleable and ductile. |
Non-metals are brittle. |
|
They produce ringing sound. |
They do not produce ringing sound. |
Question: Write the chemical properties of metals and non-metals.
Answer: Chemical Properties of Metals:
(i) Metals react with oxygen to form metal oxides.
(ii) Metals react with water to form metal hydroxide and hydrogen gas.
(iii) Metals react with acids to produce salt and hydrogen gas.
(iv) Some metals can displace less reactive metals from their compounds.
Chemical Properties of Non-metals:
(i) Non-metals react with oxygen to form non-metal oxides.
(ii) Non-metals generally do not react with water.
(iii) Non-metals do not react with acids to release hydrogen gas.
(iv) Non-metals do not displace metals from their compounds.
Question: Write the uses of metals and non-metals.
Answer: Uses of Metals:
(i) Used in making utensils (like iron, aluminium).
(ii) Used in construction of buildings, bridges (iron, steel).
(iii) Used for making wires because they conduct electricity (copper, aluminium).
(iv) Used in machinery and vehicles.
(v) Used in making jewellery (gold, silver).
Uses of Non-metals:
(i) Oxygen is used for breathing.
(ii) Nitrogen is used in fertilisers.
(iii) Carbon is used as fuel (coal) and in pencils (graphite).
(iv) Chlorine is used for water purification.
(v) Phosphorus is used in matchsticks.
Question: What happens when copper sulphate reacts with zinc? Write the chemical reaction.
Answer: When zinc is added to copper sulphate solution, a displacement reaction takes place. Zinc is more reactive than copper, so it displaces copper from the solution. As a result, the blue colour of copper sulphate fades and a reddish-brown deposit of copper is formed.
Chemical Reaction: Zn + CuSO₄ → ZnSO₄ + Cu
Question: What happens when Iron sulphate reacts with copper? Write the chemical reaction.
Answer: When iron sulphate reacts with copper, no reaction takes place. This is because copper is less reactive than iron, so it cannot displace iron from iron sulphate solution.
Chemical Reaction: Cu + FeSO₄ → No reaction
Question: What happens when Zinc sulphate reacts with iron? Write the chemical reaction.
Answer: When iron is added to zinc sulphate solution, no reaction takes place. This is because zinc is more reactive than iron, so iron cannot displace zinc from its compound.
Chemical reaction: Fe + ZnSO₄ → No reaction
1. Which of the following can be beaten into thin sheets?
(a) Zinc (b) Phosphorus (c) Sulphur (d) Oxygen
Answer: (a) Zinc .
[ Zinc is a metal, and metals are malleable, meaning they can be beaten into thin sheets.]
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
[ Most metals can be drawn into thin wires, so they are ductile. But not all metals are ductile, and non-metals are generally non-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. (F)
(b) Sodium is a very reactive metal. (T)
(c) Copper displaces zinc from zinc sulphate solution. (F)
(d) Coal can be drawn into wires. (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: The distinguish between metals and non-metals on the basis of these properties :
|
Properties |
Metals |
Non-metals |
|
1. Appearance |
Lustrous (shiny) |
Dull |
|
2. Hardness |
Hard (generally) |
Soft (generally) |
|
3. Malleability |
Can be beaten into thin sheets (malleable) |
Cannot be beaten into thin sheets (brittle/non-malleable) |
|
4. Ductility |
Can be drawn into wires (ductile) |
Cannot be drawn into wires |
|
5. Heat Conduction |
Good conductors of heat |
Poor conductors of heat (bad conductors) |
|
6. Conduction of Electricity |
Good conductors of electricity |
Poor conductors of electricity (bad conductors) |
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 foil is malleable and a good conductor of heat, so it can be easily made into thin sheets to wrap food.
(b) Immersion rods are made of metals because metals conduct heat and electricity well, helping to heat liquids quickly.
(c) Copper is less reactive than zinc, so it cannot displace zinc from its salt solution.
(d) Sodium and potassium are highly reactive metals; they react with air and water, so they are stored in kerosene to prevent reaction.
7. Can you store lemon pickle in an aluminium utensil? Explain.
Answer: No, lemon pickle should not be stored in an aluminium utensil because lemon contains acid. Acid reacts with aluminium and can spoil the food and damage the utensil.
8. 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 (f) Fuel |
Answer: (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) When dilute sulphuric acid is poured on a copper plate, no reaction occurs because copper is less reactive than hydrogen.
Copper + Dilute sulphuric acid → No reaction
(b) When iron nails are placed in copper sulphate solution, iron displaces copper from the solution. The blue solution turns green and copper is deposited.
Iron + Copper sulphate → Iron sulphate + 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) She will dissolve the gas in water and test it with blue litmus paper. The blue litmus turns red, showing the gas is acidic.
(b) The process involves two main reactions:
(i) Burning of charcoal (carbon) in air/oxygen:
Carbon + Oxygen → Carbon dioxide (C + O₂ → CO₂)
(ii) When carbon dioxide dissolves in water, it forms carbonic acid:
Carbon dioxide + Water → Carbonic acid
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: The goldsmith cleans gold jewellery using aqua regia (a mixture of hydrochloric acid and nitric acid). A small amount of gold dissolves during polishing, so its weight decreases.
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