Important Questions for CBSE Class 8 Science Chapter 4 - Materials: Metals and Non-Metals

Multiple Choice Questions (1 Mark)

1. A non-metal which is essential for living being during breathing is ________.

1. Nitrogen

2. Hydrogen

3. Carbon

4. Oxygen

Ans: D. Oxygen

2. Metallic oxides are ____________ in nature.

1. Acidic

2. Neutral

3. Basic

4. none of the above

Ans: C. Basic

3. What happens when magnesium and oxygen react?

1. magnesium hydroxide is formed

2. magnesium oxide is formed with the liberation of energy

3. magnesium does not react with oxygen

4. magnesium oxide is formed along with hydrogen gas

Ans: B. magnesium oxide is formed with the liberation of energy

4. Which one of the metals is highly reactive when exposed to oxygen and water?

1. Iron

2. Copper

3. Gold

4. Sodium

Ans: D. Sodium

5. Which one of the following is NOT a metal?

1. Sulphur

2. Mercury

3. Sodium

4. Calcium

Ans: A. Sulphur

6. Which one of the following statements is false about metals?

1. Metals are sonorous in nature.

2. Metals are bad conductors of heat and electricity.

3. Metals are hard and lustrous in appearance.

4. Metals show the property of malleability.

Ans: B. Metals are bad conductors of heat and electricity.

7. How many naturally occurring elements are there?

1. \[81\]

2. \[69\]

3. \[94\]

4. \[42\]

Ans: C. \[94\]

Very Short Answer Questions (1 Mark)

1. Name the metal which is used for decorating sweets.

Ans: Silver is used for decorating sweets.

2. A metal which is soft and can be cut with a knife is ___________.

Ans: A metal which is soft and can be cut with a knife is Sodium / Potassium.

3. Which is the only metal found in the liquid state at room temperature?

Ans: Mercury is the only metal found in the liquid state at room temperature.

4. An example of non-metal.

Ans: Carbon is an example of non-metal.

5. Name the non-metal which is very reactive when exposed to air.

Ans: Phosphorus is a non-metal which is very reactive when exposed to air.

6. The ash obtained on burning magnesium ribbon is dissolved in water is___________ in nature.

Ans: The ash obtained on burning magnesium ribbon is dissolved in water is basic in nature.

Short Answer Questions (3 Marks)

1. Classify the following into malleable and non-malleable substances.

aluminium, oxygen, gold, sulphur, potassium, carbon

Ans: Malleable substances are: aluminium, gold, potassium

Non-malleable substances are: oxygen, sulphur, carbon

2. When a zinc sulphate and copper turning are dissolved in water, reaction does not take place. Why?

Ans: When a zinc sulphate and copper turning are dissolved in water, reaction does not take place since we are trying to replace a more reactive metal with a less reactive metal which is not possible. We can conclude zinc is more reactive as compared to copper by looking at the reactivity series as well as the experimental results.

3. Complete the following reactions.

1. \[2Cu+{{H}_{2}}O+C{{O}_{2}}+{{O}_{2}}\to \]

Ans: \[2Cu+{{H}_{2}}O+C{{O}_{2}}+{{O}_{2}}\to Cu{{\left( OH \right)}_{2}}+CuC{{O}_{3}}\]

2. \[S{{O}_{3}}+{{H}_{2}}O\to \]

Ans: \[S{{O}_{3}}+{{H}_{2}}O\to {{H}_{2}}S{{O}_{4}}\]

4. Define the following.

1. Malleability

Ans: Malleability is defined as the property of metallic substances through which they can be beaten to form thin sheets of metals.

2. Ductility

Ans: Ductility is defined as the property of metallic substances through which they can be drawn into wires.

5. With an activity show that metals are sonorous.

Ans: To show that metals are sonorous take two similar boxes one made up of wood while the other made up of any metal. Now, hit the boxes against each other and note which one makes a prolonged ringing sound. The box that makes the ringing sound will turn out to be metal. Because of this property of metals, they are known to be sonorous.

6. Rajesh has four materials – wooden cork, copper coin, iron nail, ball pen in front of him. He wants to know the materials which show the property of ductility. Help him to find out the materials.

Ans: Metals show the property of ductility so Rajesh should find out which materials are made up of metals. We know that metals are sonorous, so Rajesh can simply strike the materials against each other and note which items make a ringing sound. He will find out that iron nails and copper coins are metals while wooden cork and ball pens are made up of non-metals.

7. Choose the odd one out and give reason for the same.

sodium, calcium, phosphorus, magnesium

Ans: Phosphorus is the only non-metal here and hence, the odd one out.

8. A greenish deposit is found on copper substance if it is exposed to moist air for a long time. Why?

Ans: A greenish deposit is found on copper substance if it is exposed to moist air for a long time because copper reacts with water, carbon dioxide and oxygen from the atmosphere to form copper hydroxide and copper carbonate which gives a green deposit. The chemical reaction for the same is as follows:

\[2Cu+{{H}_{2}}O+C{{O}_{2}}+{{O}_{2}}\to Cu{{\left( OH \right)}_{2}}+CuC{{O}_{3}}\]

9. Why is sodium always stored in kerosene?

Ans: Sodium is always stored in kerosene because it is very reactive and reacts vigorously with oxygen and water generating a lot of heat, if exposed to the atmosphere for long.

10. Write the chemical reaction for the following.

‘When a zinc granule is added to copper sulphate, zinc replace copper from copper sulphate. This results in disappearing of the blue colour of copper sulphate and a powdery red mass of copper are formed.’

Ans: The chemical reaction for the given situation is as follows:

\[CuS{{O}_{4}}\left( Blue \right)+Zn\to ZnS{{O}_{4}}\left( Colourless \right)+Cu\left( \operatorname{Re}d \right)\]

11. Arrange the following metals in the sequence of more reactive to less reactive.Iron, Zinc, Magnesium, Copper

Ans: The given metals in the order of more reactive to less reactive are Magnesium, Zinc, Iron, Copper.

Long Answer Questions (5 Marks)

1. List the uses of non-metals.

Ans: Some common uses of non-metals are:

1. Oxygen is a non-metal used in the respiratory process.

2. Non-metals like chlorine can be used for the purification of water.

3. Non-metals like nitrogen and potassium can be used for fertilization.

4. Phosphorus is used to make crackers.

5. Graphite, a non-metal, is used to conduct electricity.

2. Write any five differences between - metals and non-metals.

Ans: 

3. Explain the reaction of metals and non-metals with acids and bases.

Ans: Reaction of metals and non-metals with acids are:

a. Non-metals do not react with acids.

b. Metals react with acids producing a pop sound because of the release of hydrogen gas.

Reaction of metals and non-metals with bases are:

a. Reactivity of non-metals with bases gives salts and water. These reactions are quite complex since non-metal oxides are acidic in nature.

b. Reactivity of metals with bases gives salt and hydrogen gas.

4. Write the physical properties of metals.

Ans: Some physical properties of metals are:

1. They are malleable and ductile.

2. They are sonorous.

3. They have a lustrous appearance.

4. They are good conductors of heat and electricity.

5. They are hard and tough.

Short Description of Metals And Non-Metals Class 8

Metals and non-metals class 8 important questions are explained in simple steps here. These explanations are easily understood by the students and clear all doubts at once. Metal and non-metal class 8 important questions will make the subject interesting and fun to learn. Preparing these solved questions will help with homework and exams as well. Metals and non-metals class 8 important questions provide for easy exam preparation and completing homework. The solution provided will help to solve any question related to this chapter.   Metal and non-metal class 8 essential questions is a great chapter explaining the basics of Metals and non-metals. Metal and non-metal class 8 important questions are easy and scoring chapters. 

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Importance of Chapter 8

1.  Metal and non-metal class 8 important questions help to prepare for exams without any worries. It will make students work much more manageably.

2. With the Metals and Non-metals chapter, a student can learn wisely and work hard.

3. Make a routine and allot time for different subjects. Routine makes learning fun and values time. 

4. A key to good scores is to revise the previous year’s question paper from the Metal and non-metal class 8 important questions.

5.  Metal and non-metal class 8 important questions portrayed in a much simpler manner. 

6. It provides all the short answer type questions and Solved examples for the student guide.

Solved Examples

1. Write the Names of Two Soft Metals that We Can Cut Using a Knife?

Ans: Sodium and Potassium are two soft metals that we can cut using a knife.

2. Write the Definition of Malleability?

Ans: When a metal can be beaten up to a thin sheet of the piece, it must have some particular property. This exceptional property or behaviour of metal is known as Malleability.

3. Write the Definition of Ductility?

Ans: When a metal can be resized to a wire, it must have a unique property. Such a particular property of a metal is known as Ductility.

4. Show that How Metal is Sonorous?

Ans: This experiment can be quickly done using two boxes. One box should be made of wood, and the other box should be of metals. Striking on one box will produce a ringing sound. From the sound, we can understand that it is made out of metals. The other box is hence proved made of wood. The material that produces a sonorous sound is called a metal.

5. Riya Has Four Materials: Wooden Cork, Iron Ball, Copper Coin, Iron Nail. Now Help Her to Find Which Material Has More Ductility?

Ans: When a metal can be resized to a wire, it must have a particular property. Such a particular property of a metal is known as Ductility. Whenever the materials are dropped on the ground, it will create a sonorous sound that can only be created by metal. The material that produces a sonorous sound is called a metal. Copper coins and silver nails here, when dropped on the ground, will create a ringing sound. Hence it is proved that they are the only metals amongst the four materials provided.

6. When a Copper Surface is Exposed to Air For a Long Time, It Develops a Greenish Layer on its Surface. Why?

Ans: When a copper surface is exposed to air, it is in contact with carbon dioxide, water, and form hydroxides and carbonate of copper. The green coat on the surface is due to the contact with all the above materials. The green layer is formed due to copper carbonate and copper hydroxide. 

2Cu+ H2O+ CO2+O2->CU(OH)2+CUCO3

7) List the Uses of Some Non-Metals:

Ans:

1)Oxygen is used for normal breathing and respiration. Oxygen provides life.

2) Chlorine is made to purify water. 

3) Phosphorus is used to produce crackers. 

4) Non - metals like nitrogen are used in fertilizers, pesticides, and farming to grow crops. 

5) Graphite can be used as a good conductor of electricity. 

6) Potassium is used in fertilizers which are used in farms. 

7) Nitrogen is used by plants for photosynthesis. 

8) Graphite is used in making pencil leads. 

9) Carbon is used as a fuel purpose. 

10) Bromine is used in dyes and pesticides, in factories.

8. Write the Difference Between Metal and Non-Metal:

Metals and non-metals are materials that can be differentiated based on various physical and chemical properties. Metals are the elements that are generally hard and as a strong metallic bond exists between the atoms. Non-metals are the elements that are usually soft kind objects that can be cut using a knife. Non-metals do not show the properties like Malleability and Ductility. Metals make a sonorous sound also.

9. What are the Benefits of Studying Metal and Non-Metal?

Ans: All chapters that are in the book are simple to build knowledge of chemistry. Foundational concepts of chemistry are used interchangeably in many day-to-day applications, businesses, labs, and experiments. Making complex calculations to simplify problems, learning chemistry changes our minds to think broadly, in a creative manner. During the exams, if you follow these solved questions, it will clear all doubts. The questions in various competitive exams can be confusing, and the Solutions provides an easy way for students to understand concepts by breaking them down 

10. Write the Definition of Metal and Non-Metal?

Ans: Metal: Metals are opaque, lustrous elements that behave as a good conductor of heat and electricity. Most metals have malleable and ductile nature and are, on average, density is more than the other elemental substances.

Non-metal: Non-metals are natural materials that do not produce heat or electricity and have a brittle structure (can not be rolled easily, or moulded, neither can be extruded nor pressed). Chemically, hydrogen, carbon, nitrogen, oxygen, phosphorus, arsenic, and selenium are the non-metallic elements that are present in the periodic table.

11. Write About Some Applications of Metals?

Ans: Metals are used in our daily life for various purposes:

• Transportation like Cars, buses, trucks, trains, ships, and aeroplanes build materials containing metal.

• Aerospace Unmanned and human-crewed rockets and the space shuttle are also created using metals.

• Electronic devices require conductors like TV, radio, stereo, calculators, security devices, computers, etc. In our daily life application, we use such gadgets.

• Communications like a satellite communication that depends on a tough but light metal shell. Metals are persistent cause the satellites are there in space for years and hence not affected or eroded.

• Food processing and preservation in Microwave and conventional ovens and refrigerators and freezers are made of such metals that adequately keep our foods. The application of metals in our daily life is huge and unconditional

• Construction of Nails in conventional lumber construction and structural steel in other buildings also uses various metals unknown to us.

• Biomedical applications materials like artificial replacement for joints and other prostheses, metal rods, metal wires and metal plates are used inside the body.

• Electrical power production and consumption and distribution like in Boilers, turbines, generators, transformers, power lines, nuclear reactors, oil wells, and pipelines also use metals.

• Farming: Tractors, combines, planters, etc., are also made of metals.

• Household products and goods like Ovens, dish and clothes washers, vacuum cleaners, blenders, pumps, lawnmowers and trimmers, plumbing, water heaters, heating/cooling, etc. are also made of metals. The use of metals in our lives is enormous and advantageous.