Important Question Metals and Non-Metals Chapter 3 Science Class 10 CBSE Board

Short Questions Answer

1. What is malleability?
Answer: The property of metals by which they can be beaten into thin sheets is called malleability.

2. Name a metal which is a liquid at room temperature.
Answer: Mercury.

3. Which metal is the best conductor of heat?
Answer: Silver.

4. What are amphoteric oxides?
Answer: Metal oxides that react with both acids and bases to form salt and water are called amphoteric oxides.

5. Name two metals which react violently with water.
Answer: Sodium and Potassium.

6. What gas is evolved when a metal reacts with an acid?
Answer: Hydrogen gas.

7. What type of bond is formed between metals and non-metals?
Answer: Ionic or electrovalent bond.

8. Name one non-metal that is lustrous.
Answer: Iodine.

9. What is the process of coating iron with zinc called?
Answer: Galvanisation.

10. Define corrosion.
Answer: The slow eating away of metals by the action of air, moisture, or chemicals is called corrosion.

11. Which metal is used for joining railway tracks?
Answer: Aluminium (in the Thermit reaction).

12. Name the anode and cathode used in the electrolytic refining of copper.
Answer: Anode – Impure copper; Cathode – Pure copper.

13. What is an alloy?
Answer: A homogeneous mixture of two or more metals or a metal and a non-metal.

14. Why is sodium kept under kerosene?
Answer: Because it reacts vigorously with air and water.

15. Name one metal and one non-metal that are good conductors of electricity.
Answer: Metal – Copper; Non-metal – Graphite.

Long Questions Answer

1. Explain the physical properties of metals.
Answer: 

• Metals are lustrous (shiny).
• They are malleable and ductile.
• They are good conductors of heat and electricity.
• Metals are generally solid at room temperature (except mercury).
• They have high melting and boiling points and produce sound when struck (sonorous).

2. Describe the reaction of metals with water.

Answer: Metals react with water to form metal hydroxides and hydrogen gas.
Example:
2Na+2H2​O → 2NaOH+H2​↑

Sodium and potassium react violently.
Calcium reacts less vigorously.
Magnesium reacts with hot water, while zinc and iron react with steam.
Metals like lead, copper, silver, and gold do not react with water.

3. What is the reactivity series? Explain its importance.
Answer: 

The reactivity series is an arrangement of metals in the order of their decreasing reactivity.

It helps to predict:

• Which metal can displace another from its salt solution.
• The method of extraction of metals from ores.
• Which metals can react with water and acids.

4. Explain the extraction of metals in the middle of the activity series.
Answer: 

These metals (like Zn, Fe, Pb) are moderately reactive.

Their sulphide or carbonate ores are first converted into oxides by:

• Roasting: Heating sulphide ores in air.
  • 2ZnS+3O2​ → 2ZnO+2SO2​
• Calcination: Heating carbonate ores in limited air.
  • ZnCO3 → ZnO+CO2​
• Then, the metal oxides are reduced with carbon to form metals.
  • ZnO+C → Zn+CO

5. Describe the electrolytic refining of copper.
Answer: 

• Anode: Impure copper
• Cathode: Pure copper strip
• Electrolyte: Acidified copper sulphate solution
• When current passes, pure copper from the anode dissolves into the solution and deposits on the cathode.
• Impurities fall as anode mud.

6. What is corrosion? Explain the conditions necessary for rusting of iron.
Answer: 

• Corrosion is the slow destruction of metals by environmental factors like air and moisture.
• Iron rusts when exposed to both air (oxygen) and water.
• Rusting can be prevented by painting, oiling, galvanising, or making alloys like stainless steel.

7. Explain the formation of ionic compounds using the example of sodium chloride.
Answer: 

• Sodium (2,8,1) loses one electron → Na⁺
• Chlorine (2,8,7) gains one electron → Cl⁻
• Oppositely charged ions attract to form NaCl.
• Thus, NaCl is held by strong electrostatic forces.

8. What are the properties of ionic compounds?
Answer: 

• They are hard solids with high melting and boiling points.
• Soluble in water but not in organic solvents.
• Conduct electricity in molten or aqueous state.
• Brittle in nature due to strong ionic bonds.

9. Define and explain alloys with examples.
Answer: 

An alloy is a mixture of two or more metals, or a metal and a non-metal.
Purpose: To improve strength, hardness, or corrosion resistance.

Examples:

• Brass (Cu + Zn)
• Bronze (Cu + Sn)
• Solder (Pb + Sn)
• Stainless steel (Fe + Ni + Cr)

10. Describe methods of preventing corrosion.
Answer: 

• Painting / Greasing: Prevents contact with air and moisture.
• Galvanisation: Coating iron with zinc.
• Anodising: Thickening the oxide layer on aluminium.
• Alloying: Mixing iron with chromium and nickel to form rust-free stainless steel.