Materials: Metals and Non-Metals – Very Short Answer Type Questions
Class 8
Science — Chapter 4: Materials: Metals and Non-Metals
CBSE Board Examinations
How to use:
- Attempt the questions aloud or write answers in one line each.
- Use these for quick revision, oral tests and last-minute practice.
- All answers are concise — suitable for very short answer questions in exams.
1. What is malleability?
Ability of a metal to be beaten into thin sheets.
2. Define ductility.
Ability to be drawn into thin wires.
3. Give one example of a metal that is a liquid at room temperature.
Mercury.
4. What property makes metals shiny?
Metallic luster due to free electrons reflecting light.
5. What is meant by conductivity?
Ability to conduct heat or electricity.
6. Name a metal that is a good conductor of electricity.
Copper.
7. What is a physical property of non‑metals?
They are generally poor conductors and may be brittle.
8. Give an example of a non‑metal gas.
Oxygen (or nitrogen).
9. What is the typical hardness of metals compared to non‑metals?
Metals are usually harder; many non‑metals are soft or brittle.
10. Which metal is commonly used for making wires?
Copper — because it is ductile and a good conductor.
11. State one use of aluminium based on its properties.
Used in aircraft and cooking utensils for its light weight and corrosion resistance.
12. What is the appearance of most non‑metals?
Dull (not shiny) — though exceptions exist like graphite.
13. What happens when many metals react with acids?
They form a salt and hydrogen gas.
14. Give the word equation for zinc with hydrochloric acid.
Zinc + Hydrochloric acid → Zinc chloride + Hydrogen.
15. Do all metals react with water?
No — only reactive metals (e.g., sodium) react easily; others do not react with cold water.
16. What is rusting?
Corrosion of iron in presence of moisture and oxygen forming rust (hydrated iron oxide).
17. Name two factors that speed up rusting.
Presence of water (moisture) and salts (or acidic pollutants).
18. How does galvanisation prevent rusting?
A zinc coating protects iron; zinc corrodes preferentially (sacrificial protection).
19. What ion do metals typically form?
Positive ions (cations).
20. What type of oxide is formed generally when metals react with oxygen?
Metal oxides, which are often basic.
21. What type of oxide is usually formed by non‑metals with oxygen?
Non‑metal oxides, often acidic.
22. Give an example of a displacement reaction involving metals.
Zinc + Copper sulfate → Zinc sulfate + Copper (zinc displaces copper).
23. Why are some metals stored under oil?
To prevent reaction with air/moisture (e.g., sodium, potassium stored under oil).
24. What is meant by corrosion?
Gradual destruction of metals by chemical reaction with environment (e.g., rusting).
25. What is an alloy?
A mixture of two or more elements, with at least one being metal.
26. Give one example of an alloy and its components.
Steel — mainly iron with carbon.
27. Why are alloys made?
To improve properties like strength, corrosion resistance or hardness.
28. What is brass made of?
Copper and zinc.
29. Name one use of bronze.
Used in statues, bells and bearings — it is an alloy of copper and tin.
30. What property makes steel suitable for construction?
High strength and durability.
31. What is stainless steel?
An alloy of iron with chromium (and sometimes nickel) that resists rusting.
32. How does alloying affect melting point generally?
Alloys often have different melting points (usually higher or lower) than component metals; depends on composition.
33. Which alloy is used in making coins and medals?
Various alloys — historically bronze or cupro‑nickel are common.
34. What is the main use of aluminium alloys?
Lightweight structural parts (e.g., aircraft, vehicle parts).
35. How can you test if a solid is a metal using simple equipment?
Check conductivity (use a bulb or circuit), shine, malleability or magnetism (for iron).
36. What observation indicates a substance is a good conductor of electricity?
The bulb glows or the circuit completes showing current flow.
37. Describe a quick test to show whether a metal is reactive with acid.
Add dilute acid (under teacher supervision); observe bubbling of hydrogen gas if reactive.
38. What does the displacement of water method measure?
Volume of an irregular solid (by water displacement).
39. How does a burn test help classify substances? (Teacher only)
Natural fibres burn to ash; synthetic melt and form beads; some give characteristic smells.
40. Name a safety precaution during practical tests.
Wear safety goggles and perform flame tests only under teacher supervision.
41. Why is corrosion an economic problem?
It damages structures and machinery, requiring replacement/repairs which cost money.
42. Give one environmental effect of metal extraction/mining.
Habitat destruction, soil erosion and pollution of water bodies.
43. How does recycling metals help the environment?
Reduces need for mining, saves energy and lowers pollution.
44. Name one non‑metal used as a fuel.
Carbon (in the form of coal) — though coal contains other substances too.
45. Why is copper preferred for electrical wiring over aluminium in some cases?
Copper has higher conductivity and better ductility than aluminium.
46. What is a sacrificial anode?
A more reactive metal connected to a structure that corrodes instead of the protected metal.
47. Give one use of carbon in everyday life.
Pencils (graphite), filters, and as fuel in different forms.
48. Which metal is commonly used in kitchen utensils and is non‑toxic?
Stainless steel and aluminium (with proper coatings) are commonly used.
49. How is painting helpful in corrosion control?
Painting forms a protective barrier preventing contact with air and moisture.
50. What simple habit helps reduce metal waste at home?
Repairing items, reusing containers and recycling scrap metal.