CBSE Class 7 Science Chapter 4: The World of Metals and Non-metals Important Questions by PW

Understanding the properties of metals and non-metals is an important part of Class 7 Science, but remembering their characteristics and reactions can be challenging. You may find it difficult to distinguish between metals and non-metals, understand why iron rusts, identify changes in metal surfaces or explain how metals react with acids and oxygen. Applying these concepts to everyday examples also requires practice.

Class 7 Science Chapter 4 Important Questions by PW on The World of Metals and Non-metals help you revise these concepts through multiple-choice, assertion-reason, case-based and short-answer questions. Practise identifying material properties, explaining rusting, understanding metal and non-metal oxides and writing chemical equations to improve your conceptual clarity and prepare for school assessments.

CBSE Class 7 Science Chapter 4 Important Questions

Chapter 4, The World of Metals and Non-metals, asks you to know how metals and non-metals look, behave and react. The questions below cover rusting, properties of materials, reactions with acids and oxides. Each question has its answer right below it.

Multiple Choice Questions

Q1. What is the reddish-brown coating seen on iron when it is exposed to moist air?
(A) Iron sulphate

(B) Iron carbonate

(C) Rust (Iron oxide)

(D) Iron chloride

Answer: (C) Rust (Iron oxide). Iron reacts slowly with moisture and oxygen in the air and forms rust, which is written as Fe₂O₃·xH₂O.

Q2. Which of the following non-metals is soft and slippery?
(A) Diamond

(B) Graphite

(C) Sulphur

(D) Phosphorus

Answer: (B) Graphite. It is a form of carbon, and its layered structure makes it soft and slippery.

Q3. Three iron nails were dipped separately in (i) oil, (ii) water and (iii) water + air. Rusting occurred only in the third setup. Which combination is correct?
(A) Only moisture causes rusting.

(B) Only oxygen causes rusting.

(C) Rusting occurs only in the presence of heat.

(D) Both air and water are required for rusting.

Answer: (D) Both air and water are required for rusting.

Q4. Riya dropped a metal spoon and a piece of charcoal on the floor. The spoon made a ringing sound, but the charcoal made a dull thud. Which property of metals does this show?
(A) Solidity

(B) Viscosity

(C) Sonority

(D) Resistivity

Answer: (C) Sonority. Metals make a ringing sound when struck.

Q5. Assertion: Non-metals like phosphorus are stored under water. Reason: Phosphorus reacts with oxygen in air at room temperature.
(A) Both Assertion and Reason are true and Reason is the correct explanation of Assertion.
(B) Both Assertion and Reason are true and Reason is not the correct explanation of Assertion.
(C) Assertion is true, Reason is false.
(D) Both Assertion and Reason are false.

Answer: (A). Both statements are true, and the reason explains the assertion.

Q6. Suspension bridges and cranes use ropes of which material to support heavy loads?
(A) Tin

(B) Brass

(C) Steel

(D) Copper

Answer: (C) Steel.

Q7. Which pair correctly matches the property with the material?
(A) Malleable – Sulphur

(B) Ductile – Diamond

(C) Sonorous – Gold

(D) Poor conductor – Copper

Answer: (C) Sonorous – Gold.

Q8. The surface of silver objects turns ______ when exposed to air.
(A) Brown

(B) Black

(C) Blue

(D) Red

Answer: (B) Black.

Q9. Which of the following pairs is mismatched?
(A) Sodium – soft, highly reactive 

(B) Copper – ductile, good conductor 

(C) Sulphur – brittle, non-metal 

(D) Aluminium – poor conductor of electricity

Answer: (D). The pair “Aluminium – poor conductor of electricity” is the mismatched one.

Q10. Trisha visits the Statue of Liberty with her uncle. He tells her that it was shiny and reddish-brown when it was built, and it turned green over time due to air and water. Which concept from the chapter is she thinking of?
(A) Tin objects develop blue-green deposits over time in moist air.
(B) The blue colour of zinc metal is enhanced over time in polluted air.
(C) A green coating forms on the surface of copper objects kept open in the atmosphere.
(D) Reddish-brown deposits on iron objects gradually turn blue-green in the atmosphere.

Answer: (C). The statue is made of copper, and copper forms a green coating when left open in the air.

Short Answer Questions

Q11. What is the chemical formula of a metal oxide, and how are metal oxides formed?

Answer: Metal oxides form when metals react with oxygen. The formula depends on the valency of the metal. Sodium oxide (Na₂O) and magnesium oxide (MgO) are two examples.

Q12. Why do metals conduct electricity?

Answer: Metals have free electrons that move easily inside the metal. These free electrons help electric current to flow.

Q13. Why are non-metals poor conductors of heat?

Answer: The atoms in non-metals are not packed closely together. Non-metals also have no free electrons, so heat energy cannot pass through them well.

Q14. Give two examples of metals that can displace hydrogen from acids and explain how this happens.

Answer: Zinc and iron can displace hydrogen from acids. The metal atoms lose electrons and become metal ions. These ions then react with the hydrogen ions in the acid. For example, zinc reacts with hydrochloric acid like this:

Zn + 2HCl → ZnCl₂ + H₂

Hydrogen gas is displaced in this reaction. Since acids are also part of Class 7 Science, you can practise the Class 7 Science Chapter 2 important questions alongside these.

Q15. What are metal oxides and non-metal oxides? Explain their acidic or basic nature with examples.

Answer: Metal oxides form when metals react with oxygen. They are usually basic and react with acids to form salt and water. Non-metal oxides form when non-metals react with oxygen. They are generally acidic and react with bases to form salt and water.

Metal oxides are basic because they release hydroxide ions (OH⁻) in water. Non-metal oxides are acidic because they release hydrogen ions (H⁺) in water.

CBSE Class 7 Science Chapter 4 Important Questions PDF

Sometimes you want to revise without being online. The PDF keeps all 15 questions together with the answer key, so you can practise anywhere.

The PDF is made for Class 7 Chemistry and covers The World of Metals and Non-metals. After the questions, it gives an answer key and a hints and solutions section. Each solution also has a video solution button, which helps when a text answer is not enough.

How Can CBSE Class 7 Science Chapter 4 Important Questions by PW Help You?

Practising these questions helps you remember facts and also explain them in your own words. They can support your preparation in the following ways:

• Understand rusting: Learn that iron forms rust only when both air and water are present, as shown in the nail experiment.

• Remember colour changes: Recall that silver turns black, and copper forms a green coating when left in open air.

• Revise the properties of metals: Practise ideas such as sonority, malleability, ductility and conduction of electricity.

• Understand non-metals: Learn why graphite is soft and slippery and why non-metals conduct heat poorly.

• Learn reactions: Write simple equations for metals reacting with acids and for oxides reacting with water.

• Solve case-based and assertion-reason questions: Questions like Q5 and Q10 train you to connect a short story or statement to the right concept.

Before you begin, it helps to know what the chapter covers in the CBSE Class 7 Science syllabus. After practice, you can go back to the CBSE Class 7 Science notes to revise any answer you got wrong. The Class 7 Science topic notes are useful for a deeper look at each idea.

Your textbook questions matter as well. Compare your answers with the NCERT solutions for Class 7 to see how a complete answer is written. For chemical equations, the science formulas page is handy for quick revision.

Regular practice makes concepts like rusting, sonority, and oxides easier to understand and remember. Revise these important questions and explore PW’s School Prep courses for additional guidance and practice to prepare confidently for your exams.