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

Materials around us have different properties that determine how they are used in everyday life. However, distinguishing the properties of metals and non-metals and connecting them with their uses can be challenging. Questions on conductivity, malleability, rusting, reactions with oxygen and water, and the nature of metal and non-metal oxides require careful understanding of these properties.

The Class 7 Science Curiosity Chapter 4 Solutions provide clear answers to the textbook questions from The World of Metals and Non-metals. They explain the properties, reactions and applications of metals and non-metals through examples involving cooking vessels, jewellery, electrical wiring, rusting, food packaging and the preparation of metal compounds.

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

The following questions cover important properties, reactions and everyday applications of metals and non-metals.

Q1. Can you give some examples of metal sheets?

Answer: Examples of metal sheets include:

• Silver foil

• Aluminium foil

These metals can be beaten or rolled into thin sheets because of their malleability.

Q2. Can you name some metals that are used for making cooking vessels?

Answer: Metals commonly used for making cooking vessels include:

• Aluminium

• Copper

• Stainless steel

• Iron

These metals are useful for cooking vessels because they conduct heat and can be shaped into different forms.

Q3. Have you ever seen an electrician using a screwdriver? What type of material is used for making its handle?

Answer: Electricians use screwdrivers with handles made of plastic or rubber.

Plastic and rubber are poor conductors of electricity and provide insulation, helping protect the user from electric shocks.

Q4. Which metal is commonly used to make food packaging materials because it is cheaper and its thin sheets can be folded easily into any shape?

Options:

1. Aluminium

2. Copper

3. Iron

4. Gold

Answer: 1. Aluminium

Aluminium can be made into thin sheets and is commonly used for food packaging because of its malleability.

Q5. Which of the following metals catches fire when it comes in contact with water?

Options:

1. Copper

2. Aluminium

3. Zinc

4. Sodium

Answer: 4. Sodium

Sodium reacts very vigorously with water and can catch fire due to the heat produced during the reaction.

Q6. State with reason whether the following statements are True or False.

(i) Aluminium and copper are examples of non-metals used for making utensils and statues.

Answer: False

Reason: Aluminium and copper are metals, not non-metals.

(ii) Metals form oxides when combined with oxygen, the solution of which turns blue litmus paper red.

Answer: False

Reason: Metal oxides are generally basic in nature. Their aqueous solutions generally do not turn blue litmus paper red.

(iii) Oxygen is a non-metal essential for respiration.

Answer: True

Oxygen is a non-metal and is essential for respiration in living organisms.

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

Answer: False

Copper vessels are useful for boiling water because copper is a good conductor of heat, not because it conducts electricity.

Q7. Why are only a few metals suitable for making jewellery?

Answer:

Only some metals are suitable for making jewellery because they:

• Are bright and shiny.

• Are soft and easy to shape.

• Do not react easily with air and water.

• Do not corrode or lose their shine easily.

Therefore, metals such as gold and silver are commonly used for making jewellery.

Q8. Match the uses of metals and non-metals with the jumbled names.

These matches connect the properties and uses of different metals and non-metals with their everyday applications.

Q9. What happens when oxygen reacts with magnesium and sulfur? What are the main differences in the nature of the products formed?

Solution:

1. Magnesium + Oxygen

Magnesium + Oxygen → Magnesium oxide

Magnesium oxide is a basic oxide.

2. Sulfur + Oxygen

Sulfur + Oxygen → Sulfur dioxide

Sulfur dioxide is an acidic oxide.

Main difference: Magnesium is a metal and forms a basic oxide, whereas sulfur is a non-metal and forms an acidic oxide.

Q10. Complete the following flowchart.

The flowchart shows magnesium reacting with air and heat.

Step 1

Magnesium + Air + Heat → Magnesium oxide (MgO)

The ash formed is magnesium oxide (MgO).

Step 2

MgO + H₂O → Magnesium hydroxide

The product formed is magnesium hydroxide, Mg(OH)₂.

Step 3: Litmus Test

Magnesium hydroxide is basic in nature.

Q11. You are provided with iron, copper, sulfur, coal, plastic, wood and cardboard. Which material would be your choice to make a pan most suitable for boiling water and why?

Answer: Copper

Reason: A pan should be made from a good conductor of heat. Iron and copper conduct heat well, but copper conducts heat better than iron. Therefore, copper is a suitable choice for a pan used for boiling water.

Q12. Three iron nails are dipped separately in oil, water and vinegar. Which iron nail will not rust, and why?

Answer: The iron nail dipped in oil will not rust.

Reason: Rusting requires both air and water/moisture. The layer of oil prevents air and moisture from reaching the iron nail. Therefore, the nail dipped in oil does not rust.

Q13. How do the different properties of metals and non-metals determine their uses in everyday life?

The properties of metals and non-metals determine where they can be used. Some important examples are given below.

Properties and Uses of Metals

Properties and Uses of Non-metals

• Non-metals are generally poor conductors of heat and electricity.

• Sulfur and carbon can be used where insulating properties are required.

• Many non-metals are brittle.

• Sulfur and phosphorus are used in products such as matchsticks.

• Many non-metals are gases at room temperature.

• Oxygen is essential for breathing.

• Graphite, a form of carbon, is used in pencils and dry cells.

Q14. One method of protecting iron from rusting is to put a thin coating of zinc metal over it. Since sulfur does not react with water, can it be used for this purpose? Justify your answer.

Answer: No, sulfur cannot be used.

Reason: A protective coating should prevent air and water from reaching the iron and should form a strong, continuous layer. Zinc is suitable for this purpose and is used in galvanisation.

Sulfur is brittle and cannot form a strong, continuous protective coating over iron. Therefore, it cannot be used effectively to prevent rusting.

Q15. An ironsmith heats iron before making tools. Why is heating necessary in this process?

Answer:

Heating makes iron softer and easier to shape. The heated iron can be:

• Shaped

• Beaten

• Hammered

• Converted into the required tools

Therefore, heating is necessary because it makes iron easier to shape into the desired form.

NCERT Solutions for Class 7 Science Curiosity Chapter 4 PDF

Revision of metals and non-metals becomes easier when the textbook questions and answers are available together. The Class 7 Science Curiosity Chapter 4 Solutions PDF covers important questions on material properties, reactions, oxides, rusting and everyday uses for convenient practice.

NCERT Solutions for Class 7 Science Chapter 4 by PW: Key Learning Areas

The NCERT Class 7 Science Chapter 4 Solutions by PW help explain metals and non-metals through textbook questions, examples and practical situations. Key concepts covered through the solutions include:

• Properties of Metals: Understand malleability, ductility, conductivity and sonority and how these properties influence the uses of metals.

• Properties of Non-metals: Learn about the common characteristics of non-metals, including their physical states, brittleness and conductivity.

• Uses of Different Materials: Relate the properties of metals and non-metals to their uses in electrical wiring, food packaging, cooking vessels, jewellery and other applications.

• Reactions with Oxygen and Water: Understand how metals and non-metals react with oxygen and how reactive metals such as sodium interact with water.

• Metal and Non-metal Oxides: Differentiate between basic oxides such as magnesium oxide and acidic oxides such as sulfur dioxide.

• Rusting and Its Prevention: Learn about the conditions needed for rusting and how protective coatings such as zinc can protect iron from corrosion.

• Application-Based Learning: Apply concepts related to material properties and chemical reactions to answer questions based on everyday situations.

Properties such as conductivity, malleability, ductility and reactivity determine how metals and non-metals are used around us. The NCERT Class 7 Science Chapter 4 Solutions explain these properties through practical examples, reactions and application-based questions. Revising these concepts can help children understand why different materials are selected for specific purposes.

Related Resources

• CBSE Class 7 Science Syllabus

• CBSE Class 7 Science NCERT Solutions

• CBSE Class 7 Science Sample Papers

• CBSE Class 7 Science Notes