Class 8 Science Ch 4 Metals and Non-metals Oxford introduces students to the physical and chemical properties of metals and non-metals. This chapter helps in understanding the differences between the two, their uses in daily life, and how they react with air, water, acids, and bases. The concepts are explained with simple examples to make learning easy and effective.
Class 8 Science Ch 4 Metals and Non-metals Oxford-MCQ
1. Objective type questions
A. Choose the correct option.
1. Copper is a
- a. white metal
- b. greenish-yellow gas
- c. colourless gas
- d. reddish-brown metal
2. A soft metal that can be cut with a knife is
- a. gold
- b. silver
- c. potassium
- d. iron
3. The property of metals due to which they can be drawn into thin wires is
- a. malleability
- b. ductility
- c. sonority
- d. good conductors of electricity
4. Which of the following is a good conductor of heat
- a. Diamond
- b. Silver
- c. Copper
- d. All of these
5. The order of reactivity of metals is
- a. Cu > Mg> Zn > Fe
- b. Cu> Fe> Zn> Mg
- c. Mg> Zn> Fe > Cu
- d. Mg> Fe >Zn > Cu
6. A metal that will displace copper from copper sulphate solution is
- a. mercury
- b. gold
- c. aluminium
- d. silver
7. Which of following gases is produced in the reaction of a metal with an acid?
- a. Sulphur dioxide
- b. Carbon dioxide
- c. Oxygen
- d. hydrogen
8 Which of following is the least reactive metal?
- a. Gold
- b. Potassium
- c. Copper
- d. silver
9. Which of following metals is used in paints and pigments?
- a. Iron
- b. Copper
- c. Mercury
- d. Hydrogen
10. Which of following non-metals is used for making matchsticks and fireworks?
- a. Sodium
- b. Silicon
- c. Phosphorous
- d. Graphite
Ans:
- Ans: Objective Type Questions
- d) reddish-brown metal
- c) potassium
- b) ductility
- d) All of these
- c) Mg > Zn > Fe > Cu
- c) aluminium
- d) hydrogen
- a) Gold
- c) Mercury
- c) Phosphorus
Class 8 Science Ch 4 Metals and Non-metals Oxford- 1 Mark
B. Fill in the blanks with the correct words.
- The property of metals due to which they produce a ringing sound when struck with a hard object is called……(thermal conductivity/sonority).
- A non-metal that is a good conductor of heat is………………(diamond/graphite).
- A metal that burns with white dazzling light is……….(magnesium/sodium).
- Metallic oxides turn……) (red/blue) litmus solution to…………(red/blue
- ………….. (Sodium/Magnesium) is kept immersed in kerosene.
- Non-metallic oxides dissolve in water to form……….(acids,bases)
Ans:
- The property of metals due to which they produce a ringing sound when struck with a hard object is called sonority. (thermal conductivity/sonority)
- A non-metal that is a good conductor of heat is graphite. (diamond/graphite)
- A metal that burns with white dazzling light is magnesium. (magnesium/sodium)
- Metallic oxides turn red litmus solution to blue. (red/blue)
- Sodium is kept immersed in kerosene. (Sodium/Magnesium)
- Non-metallic oxides dissolve in water to form acids. (acids/bases)
II Very short answer type questions
A. Complete the equations.
- 4Na + O2→ ……………
- S + O2→………………
- CO₂ + H₂O…………………….
- 2Na + 2H2O→ 2NaOH +…………
- Zn + H₂SO₄ → + H₂……………….
Ans:
- 4Na + O₂ → 2Na₂O
- S + O₂ → SO₂
- CO₂ + H₂O → H₂CO₃ (Carbonic acid)
- 2Na + 2H₂O → 2NaOH + H₂
- Zn + H₂SO₄ → ZnSO₄ + H₂
Class 8 Science Ch 4 Metals and Non-metals Oxford- 2 Marks
III. Short answer type questions
1. Define the following terms:
- Malleability: The property of metals by which they can be beaten into thin sheets.
- Ductility: The property of metals by which they can be drawn into thin wires.
- Sonority: The property of metals that allows them to produce a ringing sound when struck.
2. State and explain how a particular property of metals helps in making the following:
Ans:
a. Wind chimes and musical instruments – Sonority: Metals produce a pleasant ringing sound when struck, making them ideal for wind chimes and musical instruments.
b. Electrical wires – Conductivity: Metals like copper and aluminium are good conductors of electricity, hence used in wiring.
c. Decorative articles and jewellery – Lustre and malleability: Metals like gold and silver are shiny and can be shaped easily, making them suitable for jewellery and decorative items.
d. Cooking utensils – Thermal conductivity: Metals like aluminium and copper conduct heat well, which helps in even cooking.
3. Compare the reactions of metals and non-metals with oxygen.
The reaction with oxygen is one of the most fundamental ways to distinguish between metals and non-metals. While both generally form oxides, the nature of these oxides and the conditions required for the reactions differ significantly.
Comparison Table: Metals vs. Non-Metals with Oxygen
| Feature | Metals | Non-Metals |
| Product Formed | Metal Oxides | Non-metal Oxides |
| Nature of Oxide | Basic (usually); some are amphoteric. | Acidic or Neutral. |
| Reaction with Water | Some dissolve to form alkalis (e.g., NaOH). | Many dissolve to form acids (e.g., H2SO4). |
| Litmus Test | Turns red litmus blue. | Turns blue litmus red (if acidic). |
| Bonding Type | Ionic bonding. | Covalent bonding. |
4. How does the sodium metal react with water? Give two examples of metals that do not react with water.
Sodium reacts vigorously with water to form sodium hydroxide and hydrogen gas, with heat and sometimes flames:
2Na + 2H₂O → 2NaOH + H₂↑
Metals that do not react with water:
Gold
Lead
5. Write one use of each of the following:
- Steel – Used in construction and making tools.
- Aluminium – Used in making utensils and aircraft parts.
- Mercury – Used in thermometers.
- Silicon – Used in making computer chips and solar panels.
- Sulphur – Used in making fertilizers and sulphuric acid.
- Diamond – Used in cutting tools and jewellery.
Class 8 Science Ch 4 Metals and Non-metals Oxford-3 Marks
IV. Long answer type questions
1. How do metals and non-metals react with acids? Write and explain the chemical equation for the reaction of magnesium with sulphuric acid and aluminium with hydrochloric acid.
Ans: Metals and Non-metals with Acids
General Reactions
Metals:
Metals react with dilute acids to form a salt and hydrogen gas (H₂).
The hydrogen gas produced can be identified by the ‘pop’ sound when a burning matchstick is brought near it.
General Reaction:
Metal + Acid → Salt + Hydrogen gas (H₂)
Non-metals:
Non-metals generally do not react with dilute acids because they cannot donate electrons to reduce hydrogen ions (H⁺) into hydrogen gas.
(a) Magnesium + Sulphuric Acid
Magnesium reacts vigorously with sulphuric acid to form magnesium sulphate and hydrogen gas.
Explanation:
Magnesium, being a reactive metal, displaces hydrogen from sulphuric acid to form magnesium sulphate and releases hydrogen gas.
(b) Aluminium + Hydrochloric Acid
Aluminium reacts with hydrochloric acid to produce aluminium chloride and hydrogen gas.
Explanation:
Initially, the reaction is slow due to the presence of a protective oxide layer (Al₂O₃) on aluminium. Once this layer is removed, the reaction becomes faster, and hydrogen gas is released.
2. Define corrosion. Explain the corrosion process in iron, copper and silver.
Ans: Corrosion is the slow deterioration of a metal due to its reaction with air, moisture, or other chemicals in the environment. It leads to the formation of compounds like oxides, sulphides, or carbonates on the surface of the metal.
Corrosion of Different Metals
(a) Corrosion of Iron (Rusting)
Iron reacts with oxygen and moisture present in the air to form rust, which is a reddish-brown flaky substance.
Chemical Reaction:
4Fe + 3O₂ + xH₂O → 2Fe₂O₃·xH₂O (Rust)
Explanation:
- Rusting requires both oxygen and water.
- The rust formed is porous and does not protect the metal.
- As a result, corrosion continues and weakens the iron.
(b) Corrosion of Copper
Copper reacts with moist air and carbon dioxide to form a green coating on its surface called patina.
Chemical Reaction:
2Cu + H₂O + CO₂ + O₂ → Cu(OH)₂·CuCO₃
Explanation:
- The green layer is basic copper carbonate.
- Unlike rust, this layer forms a protective coating and prevents further corrosion.
(c) Corrosion of Silver
Silver reacts with sulphur compounds (mainly hydrogen sulphide) present in the air to form a black coating of silver sulphide.
Chemical Reaction:
2Ag + H₂S → Ag₂S + H₂
Explanation:
The black layer dulls the shine of silver objects.
This process is called tarnishing of silver.
3. What is a displacement reaction? On the basis of the reactivity series of metals, predict whether these metals will react with each of the following salt solutions or not.
Metals: copper, magnesium, zinc, and iron
Salt solutions: copper sulphate, magnesium sulphate, zinc sulphate, and iron sulphate
Ans:
A displacement reaction is a chemical reaction in which a more reactive metal displaces a less reactive metal from its compound (usually from a salt solution).
General Form:
Metal A + Salt of Metal B → Salt of Metal A + Metal B
(Only if A is more reactive than B)
Reactivity Series Order (Relevant Metals)
Magnesium > Zinc > Iron > Copper
A metal can only displace another metal below it in this series.
Prediction Table
| Metal \ Salt Solution | Copper Sulphate (CuSO₄) | Magnesium Sulphate (MgSO₄) | Zinc Sulphate (ZnSO₄) | Iron Sulphate (FeSO₄) |
|---|---|---|---|---|
| Copper (Cu) | No reaction | No reaction | No reaction | No reaction |
| Magnesium (Mg) | Reacts | No reaction | Reacts | Reacts |
| Zinc (Zn) | Reacts | No reaction | No reaction | Reacts |
| Iron (Fe) | Reacts | No reaction | No reaction | No reaction |
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By now, you should have a clear understanding of the key concepts covered in Class 8 Science Ch 4 Metals and Non-metals Oxford. This chapter forms the foundation for many advanced topics in chemistry, so it’s important to revise it well. If you still have doubts, go through the textbook exercises and review the solutions provided here for Class 8 Science Ch 4 Metals and Non-metals Oxford. Practicing questions from Class 8 Science Ch 4 Metals and Non-metals Oxford will help strengthen your grasp on the differences, properties, and reactions of metals and non-metals.
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