Metals and Non-metals: Class 10 Important Questions with Answers

Case-based questions (4 marks each)

(i) Suggest P, Q, R and S. (1) (ii) Write the equation for R with steam. (1) (iii) Why does Q float? Why is P stored under kerosene? (2)

(i) Name X, Y and Z. (1) (ii) Name the processes and write equations for X and Y. (2) (iii) Write the reaction of Z with coke and name the type of reaction for Z. (1)

(i) Which two light the bulb? (1) (ii) Why does solid NaCl not conduct? (1) (iii) Show the formation of NaCl by electron transfer and state why NaCl has a high melting point. (2)

(i) Name the powder mixture and the reaction. (1) (ii) Write its equation and say why the iron comes out as a liquid. (1) (iii) Name the zinc coating process and explain why the bridge stays safe even if the coating gets scratched. (2)

20 MCQs (1 mark each)

1. The most ductile metal is
   (a) silver (b) gold (c) copper (d) aluminium
2. A non-metal that is lustrous:
   (a) sulphur (b) iodine (c) phosphorus (d) carbon
3. A non-metal that conducts electricity:
   (a) diamond (b) graphite (c) sulphur (d) iodine
4. Which metal melts on your palm?
   (a) sodium (b) gallium (c) lead (d) mercury
5. An amphoteric oxide is
   (a) Na₂O (b) MgO (c) ZnO (d) CaO
6. Which metal reacts only with steam?
   (a) Na (b) Ca (c) Fe (d) Cu
7. Product of iron with steam:
   (a) FeO (b) Fe₂O₃ (c) Fe₃O₄ (d) Fe(OH)₃
8. Which does not give H₂ with dilute HCl?
   (a) Zn (b) Mg (c) Fe (d) Cu
9. Aqua regia is conc. HCl and conc. HNO₃ in the ratio
   (a) 1:3 (b) 3:1 (c) 1:1 (d) 2:1
10. Electronic configuration of Mg²⁺:
    (a) 2,8,2 (b) 2,8 (c) 2,8,8 (d) 2,6
11. Ionic compounds conduct electricity
    (a) as solids (b) in kerosene (c) when molten (d) never
12. Calcination is done for
    (a) sulphide ores in excess air (b) carbonate ores in limited air (c) oxide ores with carbon (d) native metals
13. Ore of mercury:
    (a) bauxite (b) haematite (c) cinnabar (d) galena
14. The thermit reaction uses
    (a) Fe₂O₃ + C (b) Fe₂O₃ + Al (c) Al₂O₃ + Fe (d) MnO₂ + C
15. Sodium is obtained by
    (a) heating its oxide with carbon (b) electrolysis of molten NaCl (c) electrolysis of brine (d) roasting
16. In electrolytic refining of copper, the anode is
    (a) pure copper (b) impure copper (c) graphite (d) zinc
17. Galvanisation is coating iron with
    (a) tin (b) chromium (c) zinc (d) nickel
18. Solder is an alloy of
    (a) Cu + Zn (b) Cu + Sn (c) Pb + Sn (d) Fe + C
19. Black coating on silver is
    (a) Ag₂O (b) Ag₂S (c) AgCl (d) AgNO₃
20. Iron nails rust in a tube with
    (a) dry air (b) boiled water + oil (c) tap water and air (d) anhydrous CaCl₂

Answer key

Why: 10 → Mg (2,8,2) loses 2 electrons · 15 → electrolysis of brine gives NaOH, not sodium · 20 → rusting needs air and water.

Assertion–Reason (10)

(a) Both A and R true, R explains A · (b) Both true, R does not explain A · (c) A true, R false · (d) A false, R true

1. A: Sodium is stored under kerosene. R: Sodium reacts vigorously with air and moisture. → (a)
2. A: Aluminium utensils do not corrode easily. R: Aluminium is less reactive than iron. → (c) protective oxide layer
3. A: Copper does not displace hydrogen from dilute HCl. R: Copper is below hydrogen in the reactivity series. → (a)
4. A: Ionic compounds have high melting points. R: Ionic compounds are soluble in water. → (b)
5. A: Carbon cannot reduce aluminium oxide. R: Aluminium has more affinity for oxygen than carbon. → (a)
6. A: Zinc oxide is an amphoteric oxide. R: It reacts with both acids and bases to form salt and water. → (a)
7. A: Hydrogen is evolved when zinc reacts with nitric acid. R: Nitric acid is a strong oxidising agent. → (d)
8. A: Galvanised iron does not rust even if the zinc coat is scratched. R: Zinc is more reactive than iron. → (a)
9. A: Solder is used for joining electrical wires. R: Solder has a high melting point. → (c) low melting point
10. A: Gold is found in the free state. R: Gold is very malleable. → (b) free state due to low reactivity

Give reasons (2 marks each)

1. Ionic compounds conduct electricity in molten state but not in solid state.

In the solid, ions are held in fixed positions by strong forces. On melting, these forces are overcome and the ions move freely and carry current. 2

2. Sulphide ores are roasted before reduction.

It is easier to get a metal from its oxide. Roasting in excess air converts the sulphide to the oxide (2ZnS + 3O₂ → 2ZnO + 2SO₂), which is then reduced. 2

3. Electric wires are coated with PVC or rubber.

Copper wire conducts electricity; PVC/rubber are insulators that prevent electric shock and short-circuits. 2

4. Pure gold (24 carat) is not used for jewellery.

It is very soft; it is alloyed with copper or silver (22 carat) to make it hard enough for ornaments. 2

5. The thermit reaction is used to join railway tracks.

Fe₂O₃ + 2Al → 2Fe + Al₂O₃ is so exothermic that molten iron is produced, which fills the gap and joins the rails on cooling. 2