CBSE Class 10 Chemistry Metals And Non Metals Worksheet Set 20

This printable CBSE Class 10 Science worksheet for Chapter 3, Metals and Non-metals, has 26 very short answer questions with answers. It covers alloys, oxides, displacement reactions and the thermite reaction.

Very Short Answer Questions

Question 1. Explain the term malleability.
Answer:
The property of metals by virtue of which they can be beaten into thin sheets is called malleability, e.g. gold and silver.
In simple words: Malleable means beaten into sheets.

Teacher's Note:
1. Aluminium foil is an example.
2. Ductile means drawn into wires.

Question 2. Explain the term ductility.
Answer:
The ability of metals to be drawn into thin wires is called ductility. Gold is the most ductile metal.
In simple words: Ductile means drawn into wires.

Teacher's Note:
1. Copper wires are an example.
2. Malleable means beaten into sheets.

Question 3. Give one suitable word for each: (a) metal oxides which show basic as well as acidic behaviour, (b) iodine, a non-metal, is shining.
Answer:
(a) Amphoteric. (b) Lustrous.
In simple words: Amphoteric oxides react with acids and bases; lustrous means shiny.

Teacher's Note:
1. Examples: Al₂O₃ and ZnO.
2. Iodine and graphite are lustrous.

Question 4. Classify the following into acidic oxides and basic oxides: Na₂O, SO₂, MgO, CO₂.
Answer:
Acidic oxides: SO₂ and CO₂ (non-metal oxides). Basic oxides: Na₂O and MgO (metal oxides).
In simple words: Metal oxides are basic and non-metal oxides are acidic.

Teacher's Note:
1. Basic oxides turn red litmus blue.
2. Acidic oxides turn blue litmus red.

Question 5. Arrange the metals Ca, Al, Cu and Au in decreasing order of reactivity.
Answer:
Ca > Al > Cu > Au.
In simple words: Calcium is most reactive and gold least.

Teacher's Note:
1. Check against the reactivity series.
2. K, Na, Ca, Mg, Al, Zn, Fe, Pb, H, Cu, Hg, Ag, Au.

Question 6. Give reason: generally no hydrogen gas is evolved when metals react with dilute nitric acid.
Answer:
Nitric acid is a strong oxidising agent. It oxidises the hydrogen produced to water and is itself reduced to oxides of nitrogen such as NO, NO₂ or N₂O.
In simple words: HNO₃ uses up the hydrogen.

Teacher's Note:
1. Mg and Mn give hydrogen with very dilute HNO₃.
2. Other acids like HCl and H₂SO₄ give hydrogen.

Question 7. Why does calcium float in water?
Answer:
Calcium reacts with water to form hydrogen gas. The bubbles of hydrogen stick to the surface of calcium and make it float.
In simple words: Bubbles of hydrogen lift the calcium.

Teacher's Note:
1. Magnesium also floats in hot water.
2. The heat is not enough to burn the hydrogen.

Question 8. Write the chemical equation for the reaction in which zinc sulphide is heated in air.
Answer:
2ZnS + 3O₂ → 2ZnO + 2SO₂
In simple words: Roasting changes the sulphide to the oxide.

Teacher's Note:
1. SO₂ gas is given out.
2. Zinc oxide is then reduced by carbon.

Question 9. Why do ionic compounds not conduct electricity in the solid state?
Answer:
In the solid state the ions are held in fixed positions in a rigid structure and cannot move.
In simple words: Ions cannot move in the solid.

Teacher's Note:
1. They conduct when molten.
2. Free ions are needed.

Question 10. An element X forms an oxide X₂O which is neutral. Is X a metal or a non-metal?
Answer:
X is a non-metal, since only non-metals form neutral oxides (for example, H₂O).
In simple words: Metal oxides are basic or amphoteric.

Teacher's Note:
1. Neutral oxides: CO, N₂O, H₂O.
2. The oxide neither turns litmus red nor blue.

Question 11. A copper plate was dipped in silver nitrate solution and silver was deposited on the plate. Which metal is more reactive, copper or silver? Why?
Answer:
Copper is more reactive because it displaced silver from silver nitrate solution.
In simple words: Displacement shows the more reactive metal.

Teacher's Note:
1. The solution turns blue.
2. Cu + 2AgNO₃ → Cu(NO₃)₂ + 2Ag.

Question 12. Which chemical element is alloyed with copper to make bronze?
Answer:
Tin.
In simple words: Bronze is copper plus tin.

Teacher's Note:
1. Brass is copper plus zinc.
2. Bronze is used for statues.

Question 13. Name the main constituents of common brass.
Answer:
Copper and zinc.
In simple words: Brass = Cu + Zn.

Teacher's Note:
1. Used for utensils and instruments.
2. It is harder than copper.

Question 14. Which two major constituents form the alloy duralumin?
Answer:
Aluminium and copper (with small amounts of magnesium and manganese).
In simple words: Duralumin is mostly aluminium.

Teacher's Note:
1. It is strong and light.
2. Used in aircraft.

Question 15. Name the constituents of the alloy called German silver.
Answer:
Copper, zinc and nickel. It contains no silver.
In simple words: German silver has no silver in it.

Teacher's Note:
1. Looks like silver.
2. Used for utensils and ornaments.

Question 16. Choose a metal out of sodium, magnesium and iron which reacts with hot water but not with cold water. Mention the products formed.
Answer:
Magnesium. It forms magnesium hydroxide and hydrogen: Mg + 2H₂O → Mg(OH)₂ + H₂.
In simple words: Magnesium needs hot water.

Teacher's Note:
1. Sodium reacts with cold water.
2. Iron reacts only with steam.

Question 17. Which is more reactive, Ag or Pt?
Answer:
Silver is more reactive than platinum, as it lies above platinum in the reactivity series.
In simple words: Platinum is less reactive.

Teacher's Note:
1. Platinum is very unreactive.
2. It is used in jewellery.

Question 18. Write the equation for the reaction between sodium metal and cold water.
Answer:
2Na(s) + 2H₂O(l) → 2NaOH(aq) + H₂(g) + heat
In simple words: Sodium gives sodium hydroxide and hydrogen.

Teacher's Note:
1. It is highly exothermic.
2. Hydrogen catches fire.

Question 19. Why do silver ornaments turn blackish after some time?
Answer:
Silver reacts with hydrogen sulphide present in air and forms a thin layer of black silver sulphide on the surface.
In simple words: Silver tarnishes in air.

Teacher's Note:
1. The black layer is Ag₂S.
2. It can be cleaned.

Question 20. Name two metals from the following that will melt at body temperature (37 °C): gallium, magnesium, caesium, aluminium.
Answer:
Gallium and caesium.
In simple words: Gallium and caesium have very low melting points.

Teacher's Note:
1. They melt in the palm.
2. Most metals have high melting points.

Question 21. An element forms an oxide A₂O₃ which is acidic in nature. Identify A as a metal or a non-metal.
Answer:
A is a non-metal, because non-metal oxides are acidic.
In simple words: Acidic oxide means non-metal.

Teacher's Note:
1. Metal oxides are basic.
2. Example: N₂O₃.

Question 22. Name any one metal that neither reacts with cold water nor with hot water but reacts with steam to liberate hydrogen gas.
Answer:
Iron (aluminium and zinc also behave in this way). 3Fe + 4H₂O → Fe₃O₄ + 4H₂
In simple words: Iron reacts with steam only.

Teacher's Note:
1. Fe₃O₄ is formed.
2. Al forms Al₂O₃.

Question 23. Name any one metal that reacts with very dilute HNO₃ to liberate hydrogen gas.
Answer:
Magnesium (or manganese).
In simple words: Mg and Mn give hydrogen with very dilute nitric acid.

Teacher's Note:
1. Others do not.
2. Nitric acid is an oxidising agent.

Question 24. Arrange the metals Na, K, Cu and Ag in decreasing order of reactivity.
Answer:
K > Na > Cu > Ag.
In simple words: Potassium is most reactive.

Teacher's Note:
1. Use the reactivity series.
2. Silver is least reactive here.

Question 25. In the formation of the compound XY, atoms of X lose one electron each and atoms of Y gain one electron each. What is the nature of the bond in XY?
Answer:
Ionic (electrovalent) bond, formed by the transfer of electrons.
In simple words: Transfer of electrons gives an ionic bond.

Teacher's Note:
1. X forms X⁺ and Y forms Y⁻.
2. Example: NaCl.

Question 26. What is a thermite reaction?
Answer:
The reduction of iron(III) oxide by aluminium is called the thermite reaction: Fe₂O₃ + 2Al → 2Fe + Al₂O₃ + heat.
In simple words: Aluminium reduces iron oxide and gives molten iron.

Teacher's Note:
1. Used to weld railway tracks.
2. Highly exothermic.