Class 10 Science Chapter 3 Metals and Non-metals Practice Paper 4

Class: X Subject: Science Session: 2025-26 Chapter: 03 - Metals and Non-metals Time: 1½ Hours Max. Marks: 40

General Instructions:

1. All questions are compulsory.

2. This question paper contains 20 questions divided into five sections A, B, C, D and E.

3. Section A contains 10 MCQs of 1 mark each.

4. Section B contains 4 questions of 2 marks each.

5. Section C contains 3 questions of 3 marks each.

6. Section D contains 1 question of 5 marks.

7. Section E contains 2 Case Study Based questions of 4 marks each.

SECTION A - Multiple Choice Questions (1 mark each)

1. Which property allows metals to be beaten into thin sheets?
(a) Ductility
(b) Malleability
(c) Sonority
(d) Conductivity

2. Which metal is protected from corrosion by a layer of its own oxide?
(a) Iron
(b) Copper
(c) Aluminium
(d) Zinc

3. The hardest natural substance known is:
(a) Graphite
(b) Iron
(c) Diamond
(d) Platinum

4. Which of the following oxide is neutral?
(a) CO₂
(b) SO₂
(c) N₂O
(d) MgO

5. When magnesium ribbon burns in air, the flame produced is:
(a) Blue
(b) Yellow
(c) Dazzling white
(d) Green

6. An ore from which mercury is extracted is:
(a) Bauxite
(b) Cinnabar
(c) Haematite
(d) Calamine

7. Stainless steel is an alloy of:
(a) Iron, carbon and chromium
(b) Iron, nickel and chromium
(c) Iron, carbon, nickel and chromium
(d) Iron, zinc and copper

8. The reaction of iron(III) oxide with aluminium is known as:
(a) Combination reaction
(b) Decomposition reaction
(c) Displacement reaction
(d) Double displacement reaction

9. Which metal does not react with water even as steam?
(a) Aluminium
(b) Zinc
(c) Copper
(d) Iron

10. The chemical formula of rust is:
(a) Fe₂O₃
(b) FeO
(c) Fe₃O₄
(d) Fe₂O₃.xH₂O

SECTION B - Short Answer Questions (2 marks each)

11. Why are metals good conductors of heat and electricity?

12. What is the difference between calcination and roasting? Give one example of each.

13. Explain why sodium metal is stored under kerosene oil but not under water.

14. Write two methods to prevent rusting of iron.

SECTION C - Short Answer Questions (3 marks each)

15. Describe an activity to show that metals are good conductors of heat. Draw a labeled diagram.

16. What are the advantages of using alloys over pure metals? Give three examples of commonly used alloys with their composition and uses.

17. Explain the extraction of copper from copper(I) sulphide ore (Cu₂S). Write the chemical equations involved in the process.

SECTION D - Long Answer Question (5 marks)

18. Describe the chemical properties of metals with respect to their reaction with:
(a) Oxygen
(b) Water
(c) Dilute acids
(d) Salt solutions of other metals Support your answer with appropriate chemical equations.

SECTION E - Case Study Based Questions (4 marks each)

19. Case Study 1: An ancient iron pillar near the Qutub Minar in Delhi was built more than 1600 years ago. The pillar is 8 meters high and weighs 6 tonnes (6000 kg). Despite being exposed to the elements for over 16 centuries, it has not rusted significantly. Scientists from around the world have examined this pillar to understand the rust-resistant properties developed by ancient Indian metallurgists. Based on this case study, answer the following:
(a) What are the two essential conditions required for iron to rust? (1 mark)
(b) Why is the Delhi Iron Pillar scientifically significant? (1 mark)
(c) Suggest two modern methods that can be used to prevent rusting of iron structures. (2 marks)

20. Case Study 2: A chemistry student conducted a series of experiments to study the reactivity of metals. She took four metals P, Q, R, and S and performed the following tests: Test 1: When heated in air, metals P and Q burned vigorously, metal R formed a black coating, and metal S did not react. Test 2: Metals P and Q reacted violently with cold water, metal R did not react with cold water but reacted with steam, and metal S did not react even with steam. Test 3: All metals except S reacted with dilute hydrochloric acid to produce hydrogen gas.

Based on these observations, answer the following:
(a) Identify the most reactive and least reactive metals among P, Q, R, and S. (1 mark)
(b) Write the chemical equation for the reaction of metal R with steam. (Assume R is a metal like iron or zinc) (1 mark)
(c) Arrange metals P, Q, R, and S in order of decreasing reactivity. Explain how you arrived at this order. (2 marks) DETAILED ANSWER KEY - PAPER 04

SECTION A - Answers to MCQs

1.
(b) Malleability Malleability is the property of metals that allows them to be beaten into thin sheets without breaking.

2.
(c) Aluminium Aluminium develops a thin protective layer of aluminium oxide (Al₂O₃) when exposed to air, which prevents further corrosion.

3.
(c) Diamond Diamond, an allotrope of carbon, is the hardest natural substance known with very high melting and boiling points.

4.
(c) N₂O Nitrous oxide (N₂O) is a neutral oxide. It does not react with acids or bases.

5.
(c) Dazzling white When magnesium ribbon burns in air, it produces a dazzling white flame and forms magnesium oxide.

6.
(b) Cinnabar Cinnabar (HgS) is the main ore of mercury. When heated, it converts to mercuric oxide and then to mercury.

7.
(c) Iron, carbon, nickel and chromium Stainless steel is an alloy of iron mixed with carbon, nickel, and chromium. It is hard and does not rust.

8.
(c) Displacement reaction The thermit reaction (Fe₂O₃ + Al) is a displacement reaction where aluminium displaces iron from its oxide.

9.
(c) Copper Copper does not react with water in any form - neither cold water, hot water, nor steam.

10.
(d) Fe₂O₃.xH₂O Rust is hydrated iron(III) oxide represented as Fe₂O₃.xH₂O, where x represents variable amount of water.

SECTION B - Answers to Short Answer Questions

11. Metals are good conductors of heat and electricity because of the presence of free electrons in their structure. Heat conduction: When one part of a metal is heated, the free electrons gain kinetic energy and move rapidly throughout the metal, transferring heat energy quickly from the hot part to the cooler parts. Electrical conduction: When an electric potential is applied across a metal, the free electrons move from the negative terminal to the positive terminal, creating an electric current. This movement of electrons allows metals to conduct electricity efficiently.

12. Calcination: • Process of heating carbonate ores strongly in limited or absence of air • Used to convert carbonate ores into oxides • Example: ZnCO₃(s) → ZnO(s) + CO₂(g) Roasting: • Process of heating sulphide ores strongly in the presence of excess air • Used to convert sulphide ores into oxides • Example: 2ZnS(s) + 3O₂(g) → 2ZnO(s) + 2SO₂(g) 13. Sodium metal is stored under kerosene oil but not under water because: Sodium is an extremely reactive metal that reacts very vigorously with water. The reaction is highly exothermic and produces sodium hydroxide and hydrogen gas:

2Na(s) + 2H₂O(l) → 2NaOH(aq) + H₂(g) + Heat The heat produced is so much that the hydrogen gas evolved catches fire, which can cause explosion. Therefore, sodium cannot be stored in water. Kerosene oil does not react with sodium and prevents its contact with air and moisture, making it a safe storage medium. 14. Two methods to prevent rusting of iron:

1. Galvanisation: Coating iron with a thin layer of zinc. The zinc layer protects iron from rusting even if the coating is broken because zinc is more reactive than iron and prevents oxygen from reaching the iron surface.

2. Painting or Oiling: Applying paint or oil on iron surfaces creates a protective barrier that prevents air and moisture from coming in contact with iron, thus preventing rust formation. Other methods include: Greasing, Chrome plating, Anodising, or making alloys like stainless steel.

SECTION C - Answers to Short Answer Questions

15. Activity to show that metals are good conductors of heat: Materials required: Aluminium or copper wire, stand with clamp, wax, pin, burner/spirit lamp Procedure:

1. Take an aluminium or copper wire and clamp it on a stand horizontally

2. Fix a pin to the free end of the wire using wax

3. Heat the wire with a burner near the place where it is clamped

4. Observe what happens after some time Observation: After some time, the wax at the free end of the wire melts and the pin falls down. Conclusion: The heat is conducted from the heated end to the other end of the metal wire, causing the wax to melt. This proves that metals are good conductors of heat. Labeled Diagram: [The diagram should show: Stand with clamp holding metal wire horizontally, burner heating one end, wax and pin attached to free end, with labels for Stand, Clamp, Metal wire, Burner, Wax, Pin, and Free end of wire] 16.

Advantages of using alloys over pure metals:

1. Alloys are generally harder and stronger than pure metals

2. Alloys have different and often more useful properties than the constituent metals

3. Alloys can be designed to have specific properties like corrosion resistance, lower melting point, etc.

4. Alloys are often more durable and suitable for specific applications Examples of commonly used alloys:

1. Brass: • Composition: Copper (Cu) + Zinc (Zn) • Uses: Making utensils, decorative items, musical instruments, door handles • Properties: Hard, corrosion-resistant, golden appearance

2. Bronze: • Composition: Copper (Cu) + Tin (Sn) • Uses: Making statues, medals, coins, bells • Properties: Hard, resists corrosion, good casting properties

3. Stainless Steel: • Composition: Iron (Fe) + Carbon
(C) + Nickel (Ni) + Chromium (Cr) • Uses: Making cutlery, kitchen sinks, surgical instruments • Properties: Hard, does not rust, resistant to corrosion

4. Solder: • Composition: Lead (Pb) + Tin (Sn) • Uses: Welding electrical wires together • Properties: Low melting point, good electrical conductor 17. Extraction of Copper from Copper(I) Sulphide (Cu₂S): Copper is found in nature as Cu₂S. It can be obtained from its ore by just heating in air without using any reducing agent. Step 1: Roasting in Air When copper(I) sulphide is heated in air, it is partially oxidized to copper(I) oxide: 2Cu₂S(s) + 3O₂(g) → 2Cu₂O(s) + 2SO₂(g) Step 2: Reduction When the mixture of Cu₂S and Cu₂O is further heated in absence of air, the remaining Cu₂S reduces Cu₂O to give copper metal:

2Cu₂O(s) + Cu₂S(s) → 6Cu(s) + SO₂(g) Alternatively, the overall reaction can be shown as: Cu₂S(s) + O₂(g) → 2Cu(s) + SO₂(g) Note: In this process, no external reducing agent like carbon is needed. The ore itself acts as a reducing agent. The impure copper obtained is then purified by electrolytic refining to get pure copper.

SECTION D - Answer to Long Answer Question

18. Chemical Properties of Metals:
(a) Reaction with Oxygen: Almost all metals combine with oxygen to form metal oxides. Most metal oxides are basic in nature. Metal + Oxygen → Metal Oxide Examples:

1. Copper forms copper(II) oxide: 2Cu(s) + O₂(g) → 2CuO(s) (Black oxide)

2. Aluminium forms aluminium oxide: 4Al(s) + 3O₂(g) → 2Al₂O₃(s)

3. Magnesium burns with dazzling white flame: 2Mg(s) + O₂(g) → 2MgO(s) Reactivity varies: Potassium and sodium react so vigorously that they catch fire and are kept in kerosene. Silver and gold do not react with oxygen even at high temperatures. Some metal oxides are amphoteric (react with both acids and bases): Al₂O₃ + 6HCl → 2AlCl₃ + 3H₂O (acidic behavior) Al₂O₃ + 2NaOH → 2NaAlO₂ + H₂O (basic behavior)
(b) Reaction with Water: Metals react with water to produce metal oxide/hydroxide and hydrogen gas:

Metal + Water → Metal Oxide/Hydroxide + Hydrogen With Cold Water (Highly reactive metals):

1. Sodium reacts violently: 2Na(s) + 2H₂O(l) → 2NaOH(aq) + H₂(g) + Heat The reaction is so exothermic that hydrogen catches fire

2. Calcium reacts less violently: Ca(s) + 2H₂O(l) → Ca(OH)₂(aq) + H₂(g) Calcium floats due to hydrogen bubbles With Hot Water (Moderately reactive): Magnesium reacts with hot water: Mg(s) + 2H₂O(l) → Mg(OH)₂(aq) + H₂(g) With Steam (Less reactive):

1. Iron with steam: 3Fe(s) + 4H₂O(g) → Fe₃O₄(s) + 4H₂(g)

2. Zinc with steam: Zn(s) + H₂O(g) → ZnO(s) + H₂(g) Metals like copper, silver, and gold do not react with water at all.
(c) Reaction with Dilute Acids: Metals react with dilute acids to produce salt and hydrogen gas: Metal + Dilute Acid → Salt + Hydrogen gas Examples:

1. Magnesium with hydrochloric acid: Mg(s) + 2HCl(aq) → MgCl₂(aq) + H₂(g)

2. Aluminium with sulphuric acid: 2Al(s) + 3H₂SO₄(aq) → Al₂(SO₄)₃(aq) + 3H₂(g)

3. Zinc with hydrochloric acid: Zn(s) + 2HCl(aq) → ZnCl₂(aq) + H₂(g)

4. Iron with sulphuric acid: Fe(s) + H₂SO₄(aq) → FeSO₄(aq) + H₂(g) Only metals above hydrogen in the reactivity series can displace hydrogen from acids. Copper, silver, and gold do not react with dilute acids. Note: Hydrogen gas is NOT evolved when metals react with nitric acid (HNO₃) because it is a strong oxidizing agent and oxidizes H₂ to water.
(d) Reaction with Salt Solutions of Other Metals: A more reactive metal can displace a less reactive metal from its salt solution: Metal A + Salt solution of B → Salt solution of A + Metal B (More reactive) (Less reactive) Examples:

1. Iron displaces copper from copper sulphate: Fe(s) + CuSO₄(aq) → FeSO₄(aq) + Cu(s) (Brown coating of copper appears on iron nail)

2. Zinc displaces copper from copper sulphate: Zn(s) + CuSO₄(aq) → ZnSO₄(aq) + Cu(s)

3. Copper displaces silver from silver nitrate: Cu(s) + 2AgNO₃(aq) → Cu(NO₃)₂(aq) + 2Ag(s)

4. No reaction occurs when less reactive metal is used: Cu(s) + ZnSO₄(aq) → No reaction (Copper cannot displace zinc as it is less reactive) These displacement reactions help in determining the reactivity series of metals and are used to predict whether a reaction will occur or not.

SECTION E - Answers to Case Study Based Questions

19.
(a) The two essential conditions required for iron to rust are:

1. Presence of moisture (water)

2. Presence of oxygen (air) Both conditions must be present simultaneously for rusting to occur.
(b) The Delhi Iron Pillar is scientifically significant because: It demonstrates the advanced metallurgical knowledge of ancient Indian craftsmen who developed a process that prevented iron from rusting. Despite being exposed to the elements for over 1600 years, the pillar has not rusted significantly. Scientists from around the world have studied this pillar to understand the rust-resistant properties.

This shows that ancient Indians had developed superior techniques for metal treatment and protection that modern science is still trying to fully understand and replicate.
(c) Two modern methods to prevent rusting of iron structures:

1. Galvanisation: Coating iron or steel with a thin layer of zinc. The zinc layer acts as a protective barrier and prevents moisture and oxygen from reaching the iron surface. Even if the zinc coating is broken, the iron remains protected because zinc is more reactive than iron and preferentially oxidizes, protecting the iron beneath (sacrificial protection).

2. Painting: Applying layers of paint on iron surfaces creates a protective coating that prevents air and moisture from coming in direct contact with the iron. This is commonly used for iron gates, railings, bridges, and other structures. The paint must be maintained and reapplied periodically for continued protection. Other methods include: Chrome plating, powder coating, using corrosion-resistant alloys like stainless steel, or applying oil/grease (though this is temporary and mainly used for tools and machinery).

20.
(a) Based on the observations: Most reactive metals: P and Q (both react violently with cold water) Least reactive metal: S (does not react with air, water, steam, or dilute acid) Between P and Q, both are highly reactive (likely sodium/potassium group). Metal R is moderately reactive (like iron/zinc/aluminium), and metal S is least reactive (like copper/silver/gold).
(b) Assuming metal R is zinc or iron (metals that react with steam): If R is Zinc: Zn(s) + H₂O(g) → ZnO(s) + H₂(g) If R is Iron:

3Fe(s) + 4H₂O(g) → Fe₃O₄(s) + 4H₂(g) In both cases, the metal reacts with steam to form metal oxide and hydrogen gas.
(c) Order of decreasing reactivity: P ≈ Q > R > S Explanation of how this order was determined: Test 1 (Reaction with air/oxygen): • P and Q burned vigorously → Very reactive • R formed black coating → Moderately reactive (forms oxide layer) • S did not react → Least reactive Test 2 (Reaction with water): • P and Q reacted violently with cold water → Most reactive (like Na, K, Ca) • R reacted only with steam, not cold water → Moderately reactive (like Zn, Fe, Al) • S did not react even with steam → Least reactive (like Cu, Ag, Au) Test 3 (Reaction with dilute acids):

• P, Q, and R reacted with dilute HCl → Above hydrogen in activity series • S did not react with dilute acid → Below hydrogen in activity series Conclusion: Combining all three tests: • P and Q are highly reactive metals (possibly sodium and potassium) • R is moderately reactive (possibly zinc, iron, or aluminium) • S is least reactive (possibly copper, silver, or gold) This order matches the Activity Series of metals: K > Na > Ca > Mg > Al > Zn > Fe > Pb > [H] > Cu > Hg > Ag > Au The tests show that reactivity decreases from left to right, with P and Q being most reactive, followed by R, and S being least reactive.