NCERT Solutions for Class 7 Science Curiosity Chapter 4: The World of Metals and Non-metals

Question 1.
Can you give some examples of metal sheets? (Page 43)

Answer:

Some examples of metal sheets include silver foil and aluminium foil.

Question 2.

Can you name some metals that are used for making cooking vessels? (Page 46)

Answer:  Metals such as aluminium, copper, and stainless steel are widely used to make cooking utensils.

Question 3.

Have you ever seen an electrician using a screwdriver? What type of material is used for making its handle? (Page 47)

Answer: Yes. The handle of a screwdriver is usually made of plastic or rubber.

Question 1.
Which metal is commonly used to make food packaging materials as it is cheaper, and its thin sheets can be folded easily into any shape?

(i) Aluminium
(ii) Copper
(iii) Iron
(iv) Gold
(i) Aluminium

Question 2.
Which of the following metal catches fire when it comes in contact with water?

(i) Copper
(ii) Aluminium
(iii) Zinc
(iv) Sodium
(v) Sodium

Question 3.
State with reason(s) whether the following statements are True [T] or False [F].

(i) Aluminium and copper are examples of non-metals used for making utensils and statues.
(ii) Metals form oxides when combined with oxygen, the solution of which turns blue litmus paper to red.
(iii) Oxygen is a non-metal essential for respiration.

(iv) Copper vessels are used for boiling water because they are good conductors of electricity.

Answer:

[F] Aluminium and copper are metals, not non-metals.

[F] Metal oxides are basic in nature and change red litmus paper to blue.

[T] Oxygen is non-metal and is necessary for respiration.

[F] Copper vessels are used for boiling water because copper conducts heat efficiently.

Question 4.

Why are only a few metals suitable for making jewellery?

Answer: Only certain metals are used to make jewellery because they have a bright, shiny appearance. These metals are easy to mold into different shapes since they are not very hard. They also resist reactions with air and water, which helps them retain their shine without corroding or tarnishing over time.

Question 5.
Match the uses of metals and non-metals given in Column I with the jumbled names of metals and non-metals given in Column II.

Answer:

Question 6.

What happens when oxygen reacts with magnesium and sulphur. What are the main differences in the nature of products formed?

Answer:

When magnesium reacts with oxygen, it produces magnesium oxide, a basic oxide that changes red litmus paper to blue. In contrast, when sulphur combines with oxygen, it forms sulphur dioxide, an acidic oxide that turns blue litmus paper red.

Question 7.

Complete the following flowchart:

Answer:

Question 8.

You are provided with the following materials. Discuss which material would be your choice to make a pan that is most suitable for boiling water and why? 

Answer:

To boil water, the pan should be made from a material that conducts heat efficiently. Among the given options, iron and copper are metals and both conduct heat well. However, copper is the better choice because it is more resistant to rust than iron. Hence, a copper pan is the most suitable option for boiling water.

Question 9.

You are provided with three iron nails, each dipped in oil, water and vinegar. Which iron nail will not rust, and why?

Answer: An iron nail immersed in oil does not rust because the oil creates a protective coating over the metal. This layer blocks air and moisture from reaching the iron surface, thereby preventing the process of rust formation.

Question 10.

How do the different properties of metals and non-metals determine their uses in everyday life?

Answer:

Metals and non-metals possess different characteristics that determine how they are used in daily life.

Metals:

• Metals can be beaten into thin sheets (malleable); for instance, aluminium is used to make foil for food wrapping.
  
  

• They can be drawn into thin wires (ductile), which is why copper and aluminium are commonly used in electrical wiring.
  
  

• Metals produce a ringing sound when struck, a property known as sonority.
  
  

• Since they transfer heat efficiently, metals are widely used for making cooking utensils.
  
  

• Metals also allow electric current to pass through easily, making them suitable for electrical applications.
  
  

Non-metals:

• Most non-metals do not conduct heat or electricity well; materials like sulphur and carbon are used as insulators to prevent the flow of heat or current.
  
  

• Non-metals are generally brittle; substances such as sulphur and phosphorus break easily and are therefore used in matchsticks due to their reactive nature.
  
  

• Many non-metals exist as gases at room temperature, such as oxygen, which is vital for respiration.
  
  

• Non-metals usually lack shine; carbon in the form of graphite is used in pencils and dry cell batteries despite being non-lustrous.

Question 11.

One of the methods of protecting iron from getting rusted is to put a thin coating of zinc metal over it. Since sulphur does not react with water, can it be used for this purpose? Justify your answer.

Answer: No, sulphur cannot be used to protect iron from rusting. Although sulphur does not react with water, it does not form a protective coating on iron as zinc does. As a result, sulphur is unable to block air and moisture from reaching the iron surface, so it cannot prevent rusting.

Question 12.

An ironsmith heats iron before making tools. Why is heating necessary in this process?

Answer: To make tools, an ironsmith first heats a piece of iron until it becomes red-hot. Heating softens the iron, making it more malleable and easier to bend, hammer, and shape into the required form.

Activity 4.1: Let Us Explore (Pages 42-43)

Observation:

Table 4.1: Appearance, hardness, and effect of hammering on different objects or materials

Conclusion:

• Materials such as copper, aluminium, and iron have a shiny appearance, are hard, and can be hammered into thin sheets.

• Materials like coal and sulphur are dull in appearance, soft, and break easily into pieces, while wood is neither malleable nor brittle.

Activity 4.2: Let Us Investigate (Pages 45 – 46)

Observation: Metal spoon and metal coin produce a ringing sound. On the other hand, coal and wood produce dull sounds.

Conclusion: Metals are sonorous, they produce a ringing sound.

Activity 4.3: Let us Investigate (Pages 46-47)

Observation: Metal spoon is hotter to touch than wooden spoon.

Conclusion: Heat transfers through the metal spoon easily, making it hotter. While heat transfers through the wooden spoon poorly. Hence, metals are good conductors of heat, but wood is a poor conductor of heat.

Activity 4.4: Let Us Design And Create (Pages 47-48)

Observation: Table 4.2: Conduction of electricity by different objects or materials

Conclusion:

• Materials such as aluminium, iron, and copper permit the flow of electric current and are therefore good conductors of electricity.

• Materials like sulphur, coal, dry wood, stone, eraser, and nylon do not allow electric current to pass through them and are thus poor conductors of electricity.

Activity 4.5: Let Us Experiment (Pages 49-50)

Observation: Table 4.3: Formation of brown deposit on iron nails

Conclusion: The presence of both air and water is essential for the brown deposit to be formed on iron (rusting of iron).

Activity 4.6: Let Us Investigate (demonstration activity) (Page 51)

Observation:

• When magnesium ribbon is burned, it produces a bright white flame and forms a white powdery ash.
  
  

• The resulting solution turns red litmus paper blue.
  
  

Conclusion:

• Magnesium reacts with oxygen present in the air to form magnesium oxide.
  
  

• Metal oxides are usually basic in nature.

Activity 4.7: Let Us Experiment (demonstration activity) (Pages 52-53)

Observation: The solution obtained after the addition of water to the glass jar turns blue litmus paper to red.

Conclusion:
• Sulphur burns with oxygen in the air and produces sulphur dioxide gas.
• On dissolving sulphur dioxide gas in water, sulphurous acid is formed, which turns blue litmus paper to red. Thus, oxides of non-metals are acidic in nature.

Activity 4.8: Let Us Explore (Page 53) 

Observation: When sulphur is placed in water, no reaction occurs.

Conclusion: Sulphur does not react with water.

Class 7 Science Chapter 4: The World of Metals and Non-metals (2025-26 NCERT Solutions)

Explore the vital differences between metals and non-metals with these Class 7 Science NCERT Solutions. Our easy explanations help students understand topics like properties of metals, non-metal uses, and the science behind rusting, making exam preparation effortless.

Mastering the key concepts—like malleability, ductility, sonority, and conductivity—is simple with our well-structured answers. Focused study on Class 7 Science Chapter 4 ensures you remember how common metals and non-metals are used in daily life.

Regular revision with these NCERT Solutions for Class 7 Science Curiosity Chapter 4 sharpens your knowledge, boosts confidence, and prepares you for school exams and quizzes. Make learning science easier and more enjoyable, one chapter at a time!