MP Board Class 10 Science Chapter 3 Metals and Non-Metals…

MP Board Class 10 Science Chapter 3: Metals and Non-Metals Important Questions — This chapter covers the properties of metals and non-metals, their physical and chemical characteristics, reactivity series, corrosion, alloys, and extraction of metals. In MP Board exams, this chapter carries 6-8 marks with questions from all categories — MCQs, very short, short, and long answers. Practice these important questions to score full marks in the board exam 2027.

⚗️ 1. Physical Properties of Metals and Non-Metals

Q1. List the physical properties of metals with examples.

Answer: Metals possess the following physical properties:
• Lustre: Metals have a shiny appearance (e.g., gold, silver, copper)
• Malleability: Can be hammered into thin sheets (e.g., aluminium foil)
• Ductility: Can be drawn into wires (e.g., copper wire)
• Conductivity: Good conductors of heat and electricity (e.g., copper, aluminium)
• Hardness: Generally hard and solid except mercury
• Sonorous: Produce a ringing sound when struck
• Melting and Boiling Points: Generally high (except gallium and caesium)
• Density: Usually high density except sodium and potassium

Q2. What is the difference between metals and non-metals based on physical properties?

Answer: The key differences are:

Q3. Non-metals are generally non-malleable and non-ductile. Explain with examples.

Answer: Non-metals lack malleability and ductility because their atomic structure lacks free electrons that allow layers to slide over each other. For example:
• Sulphur: Cannot be hammered into sheets — it breaks into powder (brittle)
• Carbon (coal): Breaks into pieces when hammered
• Phosphorus: Very brittle and breaks easily
Non-metals cannot be drawn into wires either. The exception is carbon in the form of graphite, which is soft and a good conductor of electricity due to its layered structure.

🧪 2. Chemical Properties of Metals

Q4. Explain the reaction of metals with oxygen. Write chemical equations for at least three metals.

Answer: Metals react with oxygen to form metal oxides. These oxides are basic in nature (turn red litmus blue).

Examples:
① Sodium + Oxygen → Sodium Oxide
4Na + O₂ → 2Na₂O (Sodium burns with a yellow flame)

② Magnesium + Oxygen → Magnesium Oxide
2Mg + O₂ → 2MgO (Magnesium burns with a dazzling white light)

③ Iron + Oxygen → Iron(III) Oxide
4Fe + 3O₂ → 2Fe₂O₃ (Iron does not burn easily but forms rust in presence of moisture)

④ Copper + Oxygen → Copper(II) Oxide
2Cu + O₂ → 2CuO (Copper turns black on heating — black coating of CuO)

Q5. How do metals react with water? Give equations for sodium, calcium, and magnesium.

Answer: Different metals react with water at different rates depending on their position in the reactivity series:

① Sodium (very reactive): Reacts violently with cold water
2Na + 2H₂O → 2NaOH + H₂↑ (Exothermic — catches fire)

② Calcium (moderately reactive): Reacts less violently with cold water
Ca + 2H₂O → Ca(OH)₂ + H₂↑ (Bubbles of hydrogen gas formed)

③ Magnesium (less reactive): Reacts slowly with hot water but not with cold
Mg + 2H₂O → Mg(OH)₂ + H₂↑ (Hot water only)

Iron, Zinc: React only with steam (not liquid water)
3Fe + 4H₂O (steam) → Fe₃O₄ + 4H₂↑
Zn + H₂O (steam) → ZnO + H₂↑

Gold, Silver, Copper: Do NOT react with water at all

Q6. What happens when metals react with acids? Write reactions for magnesium, zinc, and iron with dilute HCl.

Answer: Metals above hydrogen in the reactivity series react with dilute acids to produce a salt and hydrogen gas.

General Reaction: Metal + Dilute Acid → Salt + Hydrogen (H₂↑)

① Magnesium + Hydrochloric Acid:
Mg + 2HCl → MgCl₂ + H₂↑ (Vigorous bubbling)

② Zinc + Hydrochloric Acid:
Zn + 2HCl → ZnCl₂ + H₂↑ (Moderate bubbling)

③ Iron + Hydrochloric Acid:
Fe + 2HCl → FeCl₂ + H₂↑ (Slow reaction, pale green solution of FeCl₂)

④ Aluminium + Hydrochloric Acid:
2Al + 6HCl → 2AlCl₃ + 3H₂↑

Copper, Silver, Gold — Do NOT react with dilute acids as they are below hydrogen in the reactivity series.

⚡ 3. Reactivity Series and Displacement Reactions

Q7. Write the reactivity series of metals. Why is it important?

Answer: The reactivity series arranges metals in decreasing order of their reactivity:

K > Na > Ca > Mg > Al > Zn > Fe > Sn > Pb > H > Cu > Hg > Ag > Au

Importance of Reactivity Series:
• Displacement reactions: A more reactive metal displaces a less reactive metal from its salt solution
• Extraction of metals: Determines the method of extraction — highly reactive metals (K-Al) need electrolysis, moderately reactive (Zn-Pb) are extracted by reduction with carbon, noble metals (Cu-Au) occur in native state
• Reaction with water/acids: Metals above H react with acids, those above Mg react with water
• Corrosion prediction: More reactive metals corrode faster

Q8. Explain displacement reactions with examples. What is the activity series based on?

Answer: A displacement reaction occurs when a more reactive metal removes a less reactive metal from its compound. This is the basis of extracting metals from their ores.

Example 1 — Iron displaces Copper:
Fe + CuSO₄(aq) → FeSO₄(aq) + Cu(s)
Iron (grey nail) dipped in blue copper sulphate solution → green iron sulphate + brown copper deposits on nail. The blue colour of CuSO₄ fades.

Example 2 — Zinc displaces Copper:
Zn + CuSO₄(aq) → ZnSO₄(aq) + Cu(s)

Example 3 — Zinc displaces Iron:
Zn + FeSO₄(aq) → ZnSO₄(aq) + Fe(s)

Example 4 — Copper cannot displace Iron:
Cu + FeSO₄ → No reaction (Copper is less reactive than iron)

The activity series is determined by conducting displacement experiments: if metal A displaces metal B from its salt solution, A is more reactive.

🏗️ 4. Extraction of Metals and Corrosion

Q9. Describe the different methods of extracting metals based on their reactivity.

Answer: The extraction method depends on the metal’s position in the reactivity series:

① Highly Reactive Metals (K, Na, Ca, Mg, Al):
Extracted by electrolysis of molten ores (electrolytic reduction). These metals cannot be reduced by carbon because they are stronger reducing agents than carbon.
Example: NaCl → Electrolysis → Na + Cl₂

② Moderately Reactive Metals (Zn, Fe, Pb):
Extracted by reduction with carbon (smelting). The oxide ore is heated with carbon (coke).
Example: ZnO + C → Zn + CO
Fe₂O₃ + 3CO → 2Fe + 3CO₂

③ Noble Metals (Cu, Ag, Au):
Found in native (free) state in the earth’s crust. Extracted by simple physical separation.

Q10. What is corrosion? Explain the rusting of iron with conditions required and preventive methods.

Answer: Corrosion is the gradual destruction of metals by chemical reaction with substances in their environment (air, water, acids, etc.).

Rusting of Iron:
Rust is hydrated iron(III) oxide — Fe₂O₃·xH₂O. The reaction:
4Fe + 3O₂ + 2xH₂O → 2Fe₂O₃·xH₂O

Conditions Required for Rusting:
• Presence of oxygen (from air)
• Presence of water/moisture
Both conditions are necessary — iron in dry air or in boiled water (oxygen removed) does not rust.

Methods to Prevent Rusting:
• Painting: Creates a barrier against air and moisture
• Oiling/Greasing: Used on moving parts (cycles, machinery)
• Galvanization: Coating iron with a layer of zinc (more reactive, zinc corrodes first — sacrificial protection)
• Tin/Chromium plating: Used on food containers
• Alloying: Stainless steel (Fe + Cr + Ni) resists corrosion
• Electroplating: Coating with a layer of non-corrosive metal

Q11. Silver articles turn black and copper articles turn green when exposed to air. Explain the chemical reactions.

Answer:
① Silver Tarnishing: Silver reacts with hydrogen sulphide (H₂S) present in air to form a black layer of silver sulphide.
2Ag + H₂S + ½O₂ → Ag₂S (black) + H₂O

② Copper Corrosion (Patina): Copper reacts with CO₂ and moisture in air to form a green coating of basic copper carbonate.
2Cu + H₂O + CO₂ + O₂ → CuCO₃·Cu(OH)₂ (green patina)

These are both examples of corrosion. Unlike rust on iron (which flakes and exposes fresh metal to further corrosion), the green patina on copper forms a protective layer that prevents further damage.

🔩 5. Alloys and Their Uses

Q12. What are alloys? Why are alloys preferred over pure metals? Give examples.

Answer: An alloy is a homogeneous mixture of two or more metals, or a metal with a non-metal. Alloys are designed to overcome the limitations of pure metals.

Why Alloys are Preferred:
• Increased hardness: Pure gold is soft — 22K gold (alloy with Cu/Ag) is harder
• Improved corrosion resistance: Stainless steel does not rust like iron
• Lower melting point: Solder (Pb + Sn) melts at lower temperature than either metal
• Better tensile strength: Steel is stronger than pure iron
• Desired color/appearance: 18K gold jewelry has specific shades

Examples of Alloys:

Q13. Why is stainless steel preferred for kitchen utensils? Why is it called stainless?

Answer: Stainless steel is an alloy of iron (Fe) with chromium (Cr) and nickel (Ni). It is preferred for kitchen utensils because:
• Corrosion resistant: Chromium forms a thin, invisible layer of chromium oxide on the surface that prevents rusting — making it “stainless”
• Hard and durable: Much stronger than pure iron
• Non-reactive: Does not react with food acids
• Shiny appearance: Maintains its lustre for years
• Easy to clean: Smooth surface resists bacterial growth

It is called “stainless” because unlike ordinary iron/steel, it does not form rust stains.

📝 6. Multiple Choice Questions (1 Mark Each)

MCQs on Metals and Non-Metals are frequently asked in MP Board exams. Practice these 10 questions covering properties, reactions, and applications.

1. Which of the following is the best conductor of electricity?
   (a) Silver ✓   (b) Copper   (c) Aluminium   (d) Gold
2. Which metal is liquid at room temperature?
   (a) Sodium   (b) Gallium   (c) Mercury ✓   (d) Caesium
3. The non-metal which conducts electricity is:
   (a) Diamond   (b) Graphite ✓   (c) Sulphur   (d) Iodine
4. Which metal reacts with cold water to produce hydrogen gas and catches fire?
   (a) Magnesium   (b) Calcium   (c) Sodium ✓   (d) Iron
5. What is the formula of rust?
   (a) Fe₂O₃   (b) Fe₃O₄   (c) Fe₂O₃·xH₂O ✓   (d) Fe(OH)₃
6. Which of the following metals can be cut with a knife?
   (a) Iron   (b) Aluminium   (c) Potassium ✓   (d) Copper
7. An alloy of copper and tin is called:
   (a) Brass   (b) Bronze ✓   (c) Solder   (d) Steel
8. Which gas is produced when metals react with dilute acids?
   (a) Oxygen   (b) Hydrogen ✓   (c) Chlorine   (d) Nitrogen
9. Galvanisation is coating iron with:
   (a) Copper   (b) Tin   (c) Zinc ✓   (d) Aluminium
10. The green coating on copper is basic copper:
    (a) Sulphate   (b) Chloride   (c) Carbonate ✓   (d) Nitrate

✏️ 7. Very Short & Short Answer Questions (2–4 Marks)

1. Why is aluminium used for making foil for food packaging?
   Aluminium is used because it is highly malleable (can be rolled into thin sheets), non-toxic, lightweight, and does not react with food. It also acts as a barrier against light, air, and moisture. (2 marks)
2. Why do gold and platinum not corrode in air?
   Gold and platinum are the least reactive metals (noble metals) at the bottom of the reactivity series. They do not react with oxygen, moisture, or common chemicals present in the air. That is why gold jewellery maintains its shine for centuries. (2 marks)
3. What is the thermite reaction? Write its equation and one application.
   The thermite reaction is a displacement reaction between aluminium and iron(III) oxide: 2Al + Fe₂O₃ → Al₂O₃ + 2Fe + heat. It produces molten iron at extremely high temperatures (~2500°C) and is used for welding railway tracks and joining iron parts. (3 marks)
4. Define malleability and ductility. Give one example of each.
   Malleability: The property of metals to be beaten into thin sheets. Example: Aluminium used to make foil. Ductility: The property of metals to be drawn into thin wires. Example: Copper used for electrical wires. Gold is the most malleable and ductile of all metals. (2 marks)
5. Explain with an activity how the reaction of zinc with dilute sulphuric acid produces hydrogen gas.
   Take a few zinc granules in a test tube and add dilute H₂SO₄. Bubbles of hydrogen gas are produced. Bring a burning matchstick near the mouth of the test tube — the gas burns with a popping sound, confirming it is hydrogen. Zn + H₂SO₄ → ZnSO₄ + H₂↑. (3 marks)
6. Why is sodium stored under kerosene?
   Sodium is highly reactive and catches fire spontaneously in air (reacts with oxygen and moisture vigorously). Kerosene prevents contact with air and moisture, keeping sodium safe. If exposed, sodium oxidizes to form sodium oxide and sodium hydroxide. (2 marks)
7. What is anodising? Why is it done on aluminium articles?
   Anodising is the process of forming a thick layer of aluminium oxide on aluminium by electrolysis. It protects aluminium from corrosion and makes it more resistant to wear. Anodised aluminium does not react with food acids, making it ideal for cooking utensils. (3 marks)
8. You are given three metals — Mg, Fe, Cu. Arrange them in decreasing order of their reactivity with dilute HCl.
   The decreasing order of reactivity with dilute HCl is: Mg > Fe > Cu. Magnesium reacts vigorously producing rapid bubbling. Iron reacts slowly producing moderate bubbling. Copper does not react at all with dilute HCl. (2 marks)
9. Distinguish between roasting and calcination.
   Roasting: Heating an ore in excess of air (presence of oxygen). Used for sulphide ores. Example: 2ZnS + 3O₂ → 2ZnO + 2SO₂. Calcination: Heating an ore in limited/absence of air. Used for carbonate ores. Example: ZnCO₃ → ZnO + CO₂. (3 marks)

📖 8. Long Answer Questions (5–6 Marks)

Q1. Describe the reaction of metals with oxygen, water, and acids. Write balanced chemical equations for each type of reaction using suitable examples.

Answer: Metals react differently with oxygen, water, and acids depending on their position in the reactivity series.

① Reaction with Oxygen: Metals form metal oxides (basic in nature).
4Na + O₂ → 2Na₂O (White solid, yellow flame)
2Mg + O₂ → 2MgO (White ash, dazzling light)
2Cu + O₂ → 2CuO (Black coating on heating)

② Reaction with Water:
• Very reactive (K, Na, Ca): React with cold water — 2Na + 2H₂O → 2NaOH + H₂↑
• Moderate (Mg): Reacts with hot water — Mg + H₂O → Mg(OH)₂ + H₂↑
• Less reactive (Al, Fe, Zn): React only with steam — 3Fe + 4H₂O → Fe₃O₄ + 4H₂↑
• Noble (Cu, Ag, Au): No reaction with water

③ Reaction with Dilute Acids: Metals above hydrogen displace it.
Zn + H₂SO₄ → ZnSO₄ + H₂↑
Mg + 2HCl → MgCl₂ + H₂↑
Fe + H₂SO₄ → FeSO₄ + H₂↑ (Pale green solution)
Cu, Ag, Au — no reaction (below hydrogen). (6 marks)

Q2. Explain the reactivity series of metals. How does it help in understanding displacement reactions and the extraction of metals? Give three examples of displacement reactions.

Answer: The reactivity series arranges metals in decreasing order of their chemical reactivity: K > Na > Ca > Mg > Al > Zn > Fe > Sn > Pb > H > Cu > Hg > Ag > Au.

Displacement Reactions: A more reactive metal displaces a less reactive metal from its salt solution.

Example 1: Fe + CuSO₄ → FeSO₄ + Cu (Iron displaces copper — blue CuSO₄ turns pale green)
Example 2: Zn + CuSO₄ → ZnSO₄ + Cu (Zinc displaces copper)
Example 3: Al + Fe₂O₃ → Al₂O₃ + 2Fe (Thermite reaction — Al displaces iron)

Extraction of Metals:
• Electrolytic reduction: For highly reactive metals (K to Al) — cannot be reduced by carbon
• Reduction with carbon: For moderately reactive metals (Zn to Pb) — ZnO + C → Zn + CO
• Native state: For noble metals (Cu to Au) — occur free in nature

Why this matters in MP Board exams: Questions often combine these concepts — you may be asked to predict if a displacement reaction occurs, or to suggest the extraction method for a given metal. (5 marks)

Q3. What is corrosion? Explain the rusting of iron in detail. How can rusting be prevented? Write a note on galvanization as a method of corrosion prevention.

Answer: Corrosion is the gradual deterioration of metals caused by chemical reaction with environmental substances such as oxygen, moisture, acids, or CO₂.

Rusting of Iron — Detailed Explanation:
When iron is exposed to oxygen and moisture (water), a reddish-brown coating called rust forms. Rust is chemically hydrated iron(III) oxide — Fe₂O₃·xH₂O.

Chemical Process:
• At the anode: Fe → Fe²⁺ + 2e⁻ (Iron oxidises)
• At the cathode: O₂ + 2H₂O + 4e⁻ → 4OH⁻ (Oxygen reduces)
• Overall: 4Fe + 3O₂ + 2xH₂O → 2Fe₂O₃·xH₂O

Rust is porous and flakes off, exposing fresh iron to further corrosion. This makes rusting a continuous, destructive process.

Conditions Required: Both oxygen (air) AND water must be present. Iron in dry air or in boiled water does not rust.

Prevention Methods:
1. Painting — Creates a protective barrier
2. Oiling/Greasing — For machine parts
3. Galvanization — Coating iron with molten zinc
4. Tin/Chromium plating — Food containers
5. Alloying — Making stainless steel (Fe + Cr + Ni)
6. Sacrificial protection — Attaching a more reactive metal (Mg blocks on ship hulls)

Galvanization: Iron sheets are dipped in molten zinc, forming a protective zinc coating. Zinc is more reactive than iron, so it corrodes first (sacrificial protection). Even if the coating gets scratched, zinc corrodes instead of iron. This is used on roofing sheets, buckets, pipes, and car bodies. (6 marks)

📋 Previous Year Questions (2018–2026)

❓ Frequently Asked Questions

Q1. Which is the most reactive metal and which is the least reactive?

Potassium (K) is the most reactive metal. Platinum (Pt) is the least reactive metal among common metals. Gold (Au) is also very unreactive.

Q2. Why does copper not react with dilute sulphuric acid?

Copper is below hydrogen in the reactivity series. Only metals above hydrogen can displace hydrogen from acids. Since copper is less reactive than hydrogen, no reaction occurs.

Q3. What is the difference between roasting and calcination?

Roasting is done on sulphide ores in excess air (presence of oxygen). Calcination is done on carbonate ores in limited/absence of air. SO₂ is released in roasting; CO₂ is released in calcination.

Q4. Why are ionic compounds generally hard and have high melting points?

Ionic compounds have strong electrostatic forces of attraction between oppositely charged ions. A large amount of energy is required to break these bonds, giving them high melting and boiling points and making them generally hard solids.

Q5. Why do ionic compounds conduct electricity in molten state but not in solid state?

In solid state, ions are held in fixed positions and cannot move. In molten (liquid) state, ions become free to move and can carry electrical current. Therefore, ionic compounds conduct electricity only when molten or dissolved in water.

Q6. What is aqua regia? Which metals does it dissolve?

Aqua regia is a mixture of concentrated hydrochloric acid (HCl) and concentrated nitric acid (HNO₃) in a 3:1 ratio. It can dissolve gold and platinum — the “noble metals” that do not react with individual acids.

Q7. Why are metals sonorous but non-metals are not?

Metals are sonorous because their atoms are arranged in a closely packed lattice with free electrons that can transmit vibrations. When struck, the vibrations travel through the metal, producing a ringing sound. Non-metals lack this free electron structure and do not transmit vibrations efficiently.

Q8. What is the difference between a mineral and an ore?

A mineral is a naturally occurring substance from which a metal may be extracted. An ore is a mineral from which a metal can be extracted profitably and conveniently. All ores are minerals but not all minerals are ores.

Q9. Why is aluminium used for making electrical wires despite being less conductive than copper?

Aluminium is much lighter than copper (about 1/3 the weight), cheaper, and still a good conductor. For overhead power transmission lines, its lightness reduces the load on supporting structures, making it more economical despite its slightly lower conductivity.

Q10. What happens when iron nails are placed in copper sulphate solution? Explain with colour changes.

Iron nails become coated with reddish-brown copper. The blue colour of copper sulphate solution fades and turns pale green (due to the formation of iron sulphate). This is a displacement reaction: Fe + CuSO₄ → FeSO₄ + Cu.

Q11. Why is graphite used as a lubricant and as an electrode?

Graphite is a non-metal used as a lubricant because its layers can slide over each other easily. It is used as an electrode because it is a good conductor of electricity, has a high melting point, and is chemically inert.

Q12. What is the difference between physical and chemical change in the context of metals?

A physical change does not produce a new substance — e.g., drawing a metal into wire or hammering it into a sheet. A chemical change produces a new substance — e.g., rusting of iron (Fe₂O₃·xH₂O is formed), or reaction of sodium with water (NaOH and H₂ are formed).

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