Materials Metals and Non-metals Class 8 Science Extra Questions and Answers
Materials Metals and Non-metals Class 8 Science Chapter 4 Extra Questions with Answers are provided here. We prepared these extra questions based on the latest NCERT Class 8 Science Book. CBSE Class 8 Science Chapter 4 Materials Metals and Non-metals Extra Questions will help you to properly understand a particular concept of the chapter.
Class 8 Science Chapter 4 Materials Metals and Non-metals Extra Questions
Extra Questions for Class 8 Science Chapter 4 NCERT
Very Short Answer Type Question
Question 1: Which is more reactive iron or copper?
Question 2: Which is less reactive sodium or gold?
Question 3: Which one of the two is malleable oxygen or calcium?
Question 4: Which of the two is malleable, phosphorus or iron?
Question 5: Which metal is used to make foil to wrap food items?
Answer: Aluminium metal
Question 6: Which metal foil is used to decorate sweets?
Answer: Silver foil used for decorating sweets.
Question 7: The shape of the iron nail and the aluminium wire changes on beating. Which property of metals is shown by this?
Answer: Property of malleability
Question 8: What is atom?
Answer: The smallest unit of an element is atom.
Question 9: How many naturally occurring elements are there?
Answer: There are no more than 92 naturally occurring elements.
Question 10: Why metals are said to be sonorous?
Why are metals sonorous?
Answer: Since metals produce ringing sounds, they are said to be sonorous.
Question 11: Why non-metals cannot be drawn into wires?
Answer: Non-metals are not ductile. Therefore, they cannot be drawn into wires.
Question 12: Which of the following can be beaten into thin sheets?
Question 13: 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.
Question 14: Complete the following displacement reaction:
Copper sulphate + ______ → Zinc sulphate + ______?
Answer: Copper sulphate + zinc → Zinc sulphate + copper
Question 15: Name the non-metal essential for our life, which all living being inhale during breathing.
Question 16: Which of the two will produce ringing sound a metallic box or a wooden box and why?
Answer: A metallic box will produce ringing sound because metals are sonorous.
Question 17: There are two materials A and B. On hammering A is flattened, but B breaks. Which one is a metal?
Answer: A is a metal because it flattens, i.e., it is malleable.
Question 18: Name two soft metals that can be cut with a knife.
What are soft metals that can be cut with a knife?
Why can sodium and potassium be cut with a knife?
Which metals can be cut by a knife?
Answer: Metals like sodium and potassium are soft and can be cut with a knife.
Question 19: Give some examples of non-metals.
Answer: The examples of non-metals are sulphur, carbon, oxygen, phosphorus, etc.
Question 20: Give some examples of metals.
Answer: The examples of metals are iron, copper, aluminium, calcium, magnesium, etc.
Question 21: What is malleability?
Answer: The property of metals by which they can be beaten into thin sheets is called malleability.
Question 22: What is the nature of the oxide formed by sulphur?
Answer: It is acidic in nature. Generally, oxides of non-metals are acidic in nature.
Question 23: What is ductility?
Answer: The property of metal by which it can be drawn into wires is called ductility.
Question 24: Name the product formed in the reaction of sulphur and oxygen.
Answer: The name of the product formed in the reaction of sulphur and oxygen is sulphur dioxide gas.
Question 25: What are metalloids?
Answer: Elements which possess characters of both metals and non-metals are called metalloids.
Question 26: What type of oxides is formed by metals?
What is the nature of oxides of metals?
What type of oxides is formed when metals combine with oxygen?
Answer: On burning, metals react with oxygen to produce metal oxides which are basic in nature.
Question 27: Name the metal which is found in liquid state at room temperature.
Answer: Mercury is the only metal which is found in liquid state at room temperature.
Question 28: Is rust acidic, basic or neutral in nature?
Answer: Rust i.e. Iron oxide (Fe2O3) is basic in nature. In general, metallic oxides are basic in nature.
Question 29: What type of oxides is formed by non-metals?
What is the nature of oxides of non-metals?
What type of oxides is formed when non-metals combine with oxygen?
Answer: Non-metals react with oxygen to produce non- metallic oxides which are acidic in nature.
Short Answer Type Questions
Question 1: Explain why aluminium foils are used to wrap food items.
Answer: Aluminium foils are used to wrap food items because aluminium metal is malleable. Thus, it can be beaten into thin sheets.
Question 2: What are the uses of metal?
Answer: Metals are used in making machinery, automobiles, aeroplanes, trains, satellites, industrial gadgets, cooking utensils, water boilers, etc.
Question 3: How metals and non-metals react with water?
Answer: Some metals react with water to produce metal hydroxides and hydrogen gas. Generally, nonmetals do not react with water.
Question 4: What do you mean by displacement reaction?
Answer: In displacement reaction a more reactive metal can replace a less reactive metal, but a less reactive one cannot replace a more reactive metal.
Question 5: What are the physical properties of metals?
Answer: Metals are hard, lustrous, malleable, ductile, sonorous and good conductors of heat and electricity.
Question 6: Why are sodium and potassium stored in kerosene?
Sodium and potassium are stored in kerosene. Give reason.
Answer: Sodium and potassium are stored in kerosene because they react vigorously with oxygen and water.
Question 7: What kind of handle does screw driver have and why?
Answer: Screw driver handle is either made up of wood or plastic because they are bad conductors of heat and electricity.
Question 8: Why are bells made of metal and not of wood or other material?
Why metals used for making bells?
Answer: Bells are made of metal because they are sonorous. The things made of metals produce ringing sound when struck hard.
Question 9: Is there a difference in the way metals and non-metals react with acids?
Answer: Non-metals generally do not react with acids but metals react with acids and produce hydrogen gas that burns with a ‘pop’ sound.
Question 10: Why 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.
Question 11: When materials like coal and pencil lead are beaten, their shapes do not changes, rather break down into small pieces. Why so?
Answer: This is so because coal and pencil are non-metal and they are not malleable.
Question 12: There are three materials X, Y and Z. X and Z are hard and shiny, but Y is dull and not very hard. Identify the metals and non-metals from X, Y and Z.
Answer: X and Z are metals. Y is non-metal.
Question 13: Why wires are made of aluminum and copper and not of carbon and sulphur?
Answer: Aluminum and copper are metals and can be drawn into wires. But carbon and sulphur are non-metals and hence cannot be drawn into thin wires.
Question 14: How phosphorus is stored?
Why is phosphorous stored in the water?
What will happen if phosphorus is kept in the open air?
Why do we store white phosphorus in the water?
Answer: Phosphorus is a very reactive non-metal. It catches fire if exposed to air. To prevent the contact of phosphorus with atmospheric oxygen, it is stored in water.
Question 15: Why are wooden or plastic handles used for cooking utensils?
Why can’t we hold a hot metallic pan without plastic or wooden handle without getting hurt?
Answer: Wooden or plastic handles are used for cooking utensils because they are bad conductors of heat and protects us from being hurt while handling hot things.
Question 16: Why there is difference in sound on dropping a metal coin and a piece of coal?
Answer: Metals are sonorous i.e. they produce ringing sound when struck hard whereas non-metals non-sonorous. Hence, on dropping a metal coin, ringing sound is produced but no such sound is produced in case of coal.
Question 17: What does the ‘pop’ sound indicate in a reaction?
Answer: The ‘pop’ sound indicates the presence of hydrogen gas. Metals react with sodium hydroxide to produce hydrogen gas. Reactions of non-metals with bases are complex.
Question 18: What is an element? Give example.
Answer: If a substance cannot be broken down further by chemical reactions, by cooling, heating, or by electrolysis, it is called ‘element’. Sulphur is an element. So is iron. Carbon, too, is an element.
Question 19: “The atom of an element remains unaffected by physical changes in the element.” Explain the statement with the help of example.
Answer: The atom of an element remains unaffected by physical changes in the element. For example, an atom of liquid sulphur would be exactly the same as the atom of solid or vapour sulphur.
Question 20: How are elements classified?
Answer: An important classification of elements is in terms of metals and non-metals.
Most of the elements are metals. Less than 20 are non-metals. A few are metalloids which possess characters of both metals and non-metals.
Question 21: Why are electric wire made of copper?
Why are copper metal wires used to conduct electricity?
Answer: Copper metal wires are used to conduct electricity because:
- It is ductile and can be drawn into wires.
- It is a good conductor of electricity.
Question 22: Why can’t copper displace zinc from its salt solution?
Copper cannot displace zinc from its salt solution. Give reason.
Answer: A more reactive metal can replace a less reactive metal from its compound in aqueous solution. Zinc is more reactive than copper. Therefore, copper cannot displace zinc from its salt solution.
Question 23: Can you store lemon pickle in an aluminium utensil? Explain.
Ans. 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.
Question 24: Complete the following reactions of iron and magnesium with oxygen.
Iron (Fe) + Oxygen (O2) + Water (H2O) → ?
Magnesium (Mg) + Oxygen (O2) → ?
Answer: Iron (Fe) + Oxygen (O2) + Water (H2O) → Iron oxide (Fe2O3)
Magnesium (Mg) + Oxygen (O2) → Magnesium oxide (MgO)
Question 25: Explain reaction between sulphur and oxygen. What is the nature of its oxide formed?
Answer: When sulphur burns in air, it combines with oxygen of air to form sulphur dioxide (which is an acidic oxide).
Sulphur(S) + Oxygen(O2) → Sulphur dioxide(SO2) (An acidic oxide)
Long Answer Type Answer
Question 1: Can copper displace iron from iron sulphate solution? Give reason.
Why copper cannot displace iron from iron sulphate solution?
Answer: A more reactive metal can replace a less reactive metal from its compound in aqueous solution. Copper lies below iron in the reactivity series i.e. iron is more reactive than copper. Therefore, copper cannot displace iron from its salt solutions.
Question 2: What happens when iron nails are placed in copper sulphate solution?
Answer: Iron being more reactive displaces copper from copper sulphate. In this reaction, the blue color of copper sulphate fades and there is deposition of copper on the iron nail.
Fe(Iron) + CuSO4(Copper sulphate) → FeSO4(Iron sulphate) + Cu(Copper)
Question 3: Have you ever seen a greenish deposit on the surface of copper vessels? What is that?
Why a greenish deposit is found on copper vessels in rainy season?
Why do copper vessels develop a greenish layer when exposed to moist air?
Answer: When a copper vessel is exposed to moist air for long, it acquires a dull green coating. The green material is a mixture of copper hydroxide (Cu(OH)2) and copper carbonate (CuCO3).
The following is the reaction
2Cu+H2O+CO2+O2 → Cu (OH)2 + CuCO3
Question 4: What happens when dilute sulphuric acid is poured on a copper plate?
Answer: Metals react with acids and produce hydrogen gas that burns with a ‘pop’ sound. Copper is below hydrogen in reactivity series. Thus, copper does not react with dilute sulphuric acid but it reacts with sulphuric acid on heating. Hence, no reaction will take place when dilute sulphuric acid is poured on a copper plate.
Question 5: State some of the chemical properties of non-metals.
What are the chemical properties of a non-metal?
Answer: Chemical properties of non-metals
- Non-metals react with oxygen to produce non- metallic oxides which are acidic in nature.
- Generally, non-metals do not react with water.
- Generally, non-metals do not react with acids.
Question 6: 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: In order to polish the gold ornament, it is to be dipped into a liquid called aquaregia (a mixture of hydrochloric acid and nitric acid). On getting dissolved in the environment of aquaregia, the outer layer of gold dissolves and an inner shiny layer appear. The dissolving of the layer causes a reduction in the weight of the jewelry.
Question 7: State some of the physical properties of non-metals.
Answer: Physical properties of non-metals
- They are brittle.
- They are not ductile.
- They are poor conductors of heat and electricity.
- They are dull.
- They are not strong.
- They are not sonorous.
- Most of the solid non-metals are quite soft.
Question 8: What are the uses of non-metal?
What is the importance of non-metals?
Answer: Uses of non-metal
- Non-metal essential for our life which all living beings inhale during breathing,
- Non-metals used in fertilisers to enhance the growth of plants,
- Non-metal used in water purification process,
- Non-metal used in the purple coloured solution which is applied on wounds as an antiseptic,
- Non-metals used in crackers.
Question 9: State some of the chemical properties of metals.
What are the chemical properties of a metal?
Answer: Chemical properties of metals are as follows:
- On burning, metals react with oxygen to produce metal oxides which are basic in nature.
- Some metals react with water to produce metal hydroxides and hydrogen gas.
- Metals react with acids and produce metal salts and hydrogen gas.
- Some metals react with bases to produce hydrogen gas.
- More reactive metals displace less reactive metals from their compounds in aqueous solutions.
Question 10: Some properties are listed in the following Table. Distinguish between metals and non-metals on the basis of these properties.
|Malleability||Can be beaten into thin sheets.||Cannot be beaten into thin sheets.|
|Ductility||Can be drawn into wires.||Cannot be drawn into wires.|
|Heat Conduction||Good conductor of heat.||Bad conductor of heat.|
|Conduction of Electricity||Good conductors of Electricity.||Bad conductors of Electricity.|
Question 11: 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) Add a few drops of water in the test tube containing gas. Now, cover the test tube and shake 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) Charcoal reacts with oxygen to form carbon dioxide gas.
C (carbon) + O2 (oxygen) → CO2 (Carbon dioxide)
Carbon dioxide reacts with water to form carbonic acid, which turns blue litmus paper red
CO2 (Carbon dioxide) + H2O(Water) → H2CO3 (Carbonic acid)
Question 12: When an iron knife is kept dipped in blue copper sulphate solution the solution changes to light green. Why?
What happens when a piece of iron metal is placed in copper sulphate solution name the type of reaction involved?
Answer: When iron is placed in copper sulphate solution for some time, then the blue colour of copper sulphate solution fades and a red-brown coating of copper metal is deposited on the piece of iron. This reaction can be written as:
Copper sulphate(CuSO4) + Iron(Fe) → Iron sulphate(FeSO4) + copper(Cu)
Here, the Iron sulphate solution turns greenish due to the formation of iron sulphate. In this reaction, a more reactive metal ‘iron’ displaces a less reactive metal ‘copper’ from its salt solution, copper sulphate solution.
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