Metals and Non Metals — Class 10 Chemistry NCERT Solutions (Free)
Free step-by-step NCERT solutions for Class 10 Chemistry chapter "Metals and Non Metals" — 10 important questions with detailed answers for CBSE board exam preparation.
TL;DR: Free step-by-step NCERT solutions for Class 10 Chemistry chapter "Metals and Non Metals" — 10 important questions with detailed answers for CBSE board…
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NCERT Solutions for Class 10 Chemistry — Metals and Non Metals. Step-by-step answers to all 10 textbook questions from this chapter, written for CBSE board preparation and free to use.
Metals and Non Metals — All 10 Questions Solved
Q1. Define metals and non-metals based on their physical properties. Give two examples of each.
Metals are elements that generally have a shiny appearance, are malleable, ductile, and are good conductors of heat and electricity. They are solid at room temperature (except mercury).
Examples: Copper (Cu), Iron (Fe)
Non-metals are elements that are generally dull in appearance, brittle, and are poor conductors of heat and electricity. They can exist in solid, liquid, or gaseous states at room temperature.
Examples: Oxygen (O2), Sulfur (S)
Q2. Explain the difference between the reactivity of metals and non-metals with oxygen. Illustrate with equations.
Metals generally react with oxygen to form basic oxides (metal oxides).
Example: 2Mg + O2 -> 2MgO (Magnesium oxide is basic)
Non-metals react with oxygen to form acidic oxides (non-metal oxides).
Example: S + O2 -> SO2 (Sulfur dioxide is acidic)
The oxides of metals are typically basic and turn red litmus paper blue. The oxides of non-metals are typically acidic and turn blue litmus paper red. This difference is due to the nature of bonding—metals form ionic bonds with oxygen, while non-metals form covalent bonds.
Q3. What is the reactivity series of metals? Arrange these metals in order of their reactivity: Copper, Magnesium, Iron, Calcium.
The reactivity series of metals is the arrangement of metals in the order of their decreasing reactivity. More reactive metals displace less reactive metals from their salt solutions.
Arrangement in decreasing order of reactivity:
Calcium (Ca) > Magnesium (Mg) > Iron (Fe) > Copper (Cu)
Calcium is most reactive because it loses electrons easily, while Copper is least reactive among these four metals. This series helps predict displacement reactions. For example, Magnesium can displace Iron from Iron sulfate solution: Mg + FeSO4 -> MgSO4 + Fe
Q4. Explain roasting and calcination. How are they used in the extraction of metals?
Both are processes used to convert ore into metal oxides for extraction:
Roasting:
- The process of heating an ore in excess of air/oxygen below its melting point
- Used for sulfide ores
- Example: 2ZnS + 3O2 -> 2ZnO + 2SO2
- The zinc sulfide is converted to zinc oxide
Calcination:
- The process of heating an ore in the absence or limited supply of air below its melting point
- Used for carbonate and hydrated ores
- Example: CaCO3 -> CaO + CO2 (heating of limestone)
- The carbonate is decomposed to metal oxide
Both processes remove water and gases from the ore, making it easier to reduce the oxide to pure metal. The resulting metal oxide is then reduced using carbon (in reduction step) to get the pure metal.
Q5. What is reduction in the context of metal extraction? Explain with a suitable example.
Reduction is the process of removing oxygen from a compound. In metal extraction, it refers to converting a metal oxide into a pure metal by removing oxygen.
Most commonly, carbon (in the form of coke) is used as a reducing agent.
Example: Extraction of Iron from Iron oxide
2Fe2O3 + 3C -> 4Fe + 3CO2
Or in a blast furnace:
2Fe2O3 + 3CO -> 4Fe + 3CO2
Here, carbon and carbon monoxide reduce the iron oxide to iron by removing the oxygen. The oxygen atoms combine with carbon/CO to form CO2, leaving behind pure iron.
Other reducing agents include aluminum and hydrogen. Aluminum is used for oxides of less reactive metals. The choice of reducing agent depends on the reactivity of the metal—more reactive metals require stronger reducing agents.
Q6. Write the chemical equations for the reaction of Sodium metal with water and dilute hydrochloric acid.
Reaction with Water:
2Na + 2H2O -> 2NaOH + H2
Sodium reacts vigorously with water. The reaction is highly exothermic (releases heat). Sodium floats on water because it is less dense than water. The hydrogen gas produced ignites due to heat, producing a pop sound. Sodium hydroxide (NaOH) formed dissolves in water and the solution is alkaline (basic).
Reaction with Dilute Hydrochloric Acid:
2Na + 2HCl -> 2NaCl + H2
Sodium reacts violently with dilute HCl. The reaction is even more vigorous than with water because HCl is a stronger acid. Hydrogen gas is produced and ignites spontaneously due to the intense heat released. Sodium chloride (NaCl) is formed as the salt. The reaction demonstrates sodium's high reactivity.
Q7. What are ionic compounds? Explain the properties of ionic compounds with examples.
Ionic compounds are compounds formed between metals and non-metals through the transfer of electrons from metal atoms to non-metal atoms. The metal atom loses electrons to form a cation (positive ion), and the non-metal atom gains electrons to form an anion (negative ion). These ions are held together by strong electrostatic attraction (ionic bonds).
Examples: NaCl (Sodium chloride), MgO (Magnesium oxide), CaCl2 (Calcium chloride)
Properties of Ionic Compounds:
1. State: Solid at room temperature (except NH4Cl which is white solid with pungent odor)
2. Melting and Boiling Points: High melting and boiling points due to strong ionic bonds. Example: NaCl melts at 801°C
3. Electrical Conductivity: Conduct electricity in molten state or aqueous solution but not in solid state (electrons are fixed in crystal lattice)
4. Solubility: Most ionic compounds are soluble in polar solvents like water, but insoluble in non-polar solvents like benzene
5. Hardness: Hard and brittle; easily break into pieces when force is applied
6. Nature: Generally show basic nature if formed from metal and non-metal
Q8. Define corrosion and explain how rusting of iron occurs. Write the chemical equation.
Corrosion is the process of deterioration of metals and alloys due to reaction with atmospheric oxygen and moisture.
Rusting of Iron:
Rusting is the corrosion of iron and is one of the most common and destructive forms of corrosion. Iron rusts when exposed to oxygen and moisture (water).
Chemical Equation:
4Fe + 3O2 + 6H2O -> 4Fe(OH)3
Or:
4Fe(OH)3 -> 2Fe2O3.3H2O (hydrated iron oxide - rust)
Process:
1. Iron first reacts with water to form iron hydroxide
2. In the presence of dissolved oxygen, iron hydroxide is oxidized to iron(III) hydroxide
3. Iron(III) hydroxide is dehydrated to form hydrated iron oxide (rust)
4. Rust is reddish-brown in color
Conditions required for rusting:
- Presence of iron or iron alloy
- Presence of oxygen from air
- Presence of moisture (water)
- All three conditions must be present together for rusting to occur
Q9. Explain methods to prevent corrosion of metals. Give practical examples.
Prevention of corrosion is important to protect metals from deterioration. The main principle is to prevent contact between the metal and the corrosive agents (oxygen and moisture).
Methods to Prevent Corrosion:
1. Painting:
- Coat the metal surface with paint
- Paint prevents oxygen and moisture from reaching the metal
- Used for iron bridges, gates, car bodies
2. Oiling/Greasing:
- Apply thin layer of oil or grease on the metal surface
- Prevents moisture from reaching the metal
- Used for machinery parts, tools
3. Galvanization:
- Coat iron with a layer of zinc by dipping in molten zinc
- Zinc acts as a protective layer and is more reactive than iron
- Used for steel pipes, water tanks, roof sheets
4. Tinplating:
- Coat iron with a thin layer of tin
- Tin protects iron from oxygen and moisture
- Used for tin cans, food containers
5. Electroplating:
- Deposit a thin layer of an unreactive metal (like nickel or chromium) on a reactive metal
- Electroplating with chromium gives shine and prevents corrosion
- Used for car parts, jewelry
6. Alloy Formation:
- Mix iron with other metals to form alloys that are more resistant to corrosion
- Stainless steel (iron + chromium + nickel) does not rust
- Used for cutlery, surgical instruments
7. Keeping the metal dry:
- Store metals in dry places
- Remove moisture promptly
- Use desiccants (substances that absorb moisture)
Q10. Compare the reactivity of zinc and copper with dilute sulfuric acid. Explain why they differ in reactivity.
Reactivity with Dilute Sulfuric Acid:
Zinc:
Zn + H2SO4 -> ZnSO4 + H2
Zinc reacts vigorously with dilute sulfuric acid. Hydrogen gas is produced rapidly. The solution becomes warm due to exothermic reaction. Zinc sulfate is formed.
Copper:
Copper does NOT react with dilute sulfuric acid under normal conditions.
Cu + H2SO4 (dilute) -> No reaction
No hydrogen gas is produced. Copper remains unreacted.
Reason for Difference in Reactivity:
1. Position in Reactivity Series:
Zinc is above hydrogen in the reactivity series, so it can displace hydrogen from dilute acids.
Copper is below hydrogen in the reactivity series, so it cannot displace hydrogen from dilute acids.
2. Electron Loss Tendency:
Zinc has a greater tendency to lose electrons (lower ionization energy) compared to copper. Zinc atoms easily form Zn2+ ions by donating electrons to H+ ions of the acid.
Copper has a lower tendency to lose electrons. Cu atoms cannot easily form Cu2+ ions to displace hydrogen.
3. Standard Reduction Potentials:
Zinc has a more negative reduction potential than hydrogen, making it a stronger reducing agent.
Copper has a positive reduction potential, making it a weaker reducing agent than hydrogen.
Note: Copper reacts with concentrated sulfuric acid and dilute nitric acid, but not with dilute sulfuric acid or dilute hydrochloric acid.
Metals and Non Metals — Practice MCQs with Answers
Attempt these 20 multiple-choice questions after working through the solutions above. Each carries the correct option and the reasoning behind it, so a wrong answer tells you which idea to revisit.
MCQ 1. Which of the following properties is generally exhibited by metals?
- A. Brittleness
- B. Malleability
- C. Poor electrical conductivity
- D. Low melting point
Answer: B. Malleability — Metals are typically malleable, meaning they can be hammered into thin sheets without breaking. Brittleness and poor electrical conductivity are characteristics of non-metals, while metals generally have high melting points.
MCQ 2. Sodium metal is stored in kerosene oil because:
- A. It is highly reactive with water and air.
- B. It reacts with kerosene to form a protective layer.
- C. Kerosene is a good solvent for sodium.
- D. It prevents rust formation.
Answer: A. It is highly reactive with water and air. — Sodium is a highly reactive metal that readily reacts with moisture (water) and oxygen (air) in the atmosphere. Storing it in kerosene prevents these reactions by isolating it from air and water.
MCQ 3. Which of the following statements about non-metals is generally INCORRECT?
- A. They are poor conductors of heat and electricity.
- B. They form acidic or neutral oxides.
- C. They are generally found as solids or gases at room temperature.
- D. They are lustrous and ductile.
Answer: D. They are lustrous and ductile. — Non-metals are generally non-lustrous and non-ductile (brittle if solid). Lustre and ductility are characteristic properties of metals.
MCQ 4. Which of the following metals will displace hydrogen from dilute acids?
- A. Copper
- B. Silver
- C. Magnesium
- D. Gold
Answer: C. Magnesium — Metals that are more reactive than hydrogen (i.e., above hydrogen in the reactivity series) can displace hydrogen from dilute acids. Magnesium is above hydrogen, while copper, silver, and gold are below hydrogen.
MCQ 5. Ionic compounds are generally characterized by:
- A. Low melting and boiling points.
- B. Poor electrical conductivity in molten state.
- C. Solubility in organic solvents.
- D. High melting and boiling points.
Answer: D. High melting and boiling points. — Ionic compounds have strong electrostatic forces of attraction between ions, requiring a large amount of energy to break them, leading to high melting and boiling points. They are good conductors in molten or aqueous states, and generally insoluble in organic solvents.
MCQ 6. Which of the following methods is used for the extraction of highly reactive metals like sodium and aluminium?
- A. Heating with carbon
- B. Roasting followed by reduction
- C. Electrolytic reduction of their molten chlorides/oxides
- D. Calcination followed by reduction
Answer: C. Electrolytic reduction of their molten chlorides/oxides — Highly reactive metals have a strong affinity for oxygen and cannot be reduced by carbon. Therefore, they are extracted by the electrolytic reduction of their molten compounds.
MCQ 7. Galvanisation is a method of protecting iron from rusting by coating it with a thin layer of which metal?
- A. Copper
- B. Aluminium
- C. Zinc
- D. Tin
Answer: C. Zinc — Galvanisation involves coating iron articles with a layer of zinc. Zinc is more reactive than iron and protects it cathodically, even if the coating is broken.
MCQ 8. Which non-metal is an excellent conductor of electricity?
- A. Sulphur
- B. Carbon (in the form of graphite)
- C. Phosphorus
- D. Iodine
Answer: B. Carbon (in the form of graphite) — Graphite, an allotrope of carbon, is unique among non-metals for being a good conductor of electricity due to the presence of free electrons.
MCQ 9. An oxide which reacts with both acids and bases to produce salt and water is called an:
- A. Acidic oxide
- B. Basic oxide
- C. Amphoteric oxide
- D. Neutral oxide
Answer: C. Amphoteric oxide — Amphoteric oxides exhibit both acidic and basic properties, meaning they can react with both acids and bases to form salt and water. Aluminium oxide and zinc oxide are common examples.
MCQ 10. When zinc granules are added to a solution of copper sulphate, what observation is made?
- A. The solution turns blue.
- B. No reaction occurs.
- C. A reddish-brown deposit is formed, and the blue colour of the solution fades.
- D. Hydrogen gas is evolved.
Answer: C. A reddish-brown deposit is formed, and the blue colour of the solution fades. — Zinc is more reactive than copper, so it displaces copper from copper sulphate solution. This forms zinc sulphate (colourless solution) and deposits reddish-brown copper metal. The blue colour of CuSO4 fades.
MCQ 11. The property of metals by which they can be drawn into thin wires is called:
- A. Malleability
- B. Sonority
- C. Ductility
- D. Lustre
Answer: C. Ductility — Ductility is the characteristic property of metals that allows them to be drawn into thin wires. Malleability refers to hammering into sheets, sonority to producing sound, and lustre to shininess.
MCQ 12. Which of the following metals reacts vigorously with cold water to produce hydrogen gas?
- A. Iron
- B. Magnesium
- C. Sodium
- D. Copper
Answer: C. Sodium — Highly reactive metals like sodium react violently with cold water, producing sodium hydroxide and hydrogen gas, often with a release of so much heat that the hydrogen ignites. Iron reacts with steam, and magnesium reacts with hot water.
MCQ 13. In the formation of an ionic compound, atoms transfer electrons. Which statement correctly describes this transfer?
- A. Metals lose electrons to form anions, and non-metals gain electrons to form cations.
- B. Metals gain electrons to form cations, and non-metals lose electrons to form anions.
- C. Metals lose electrons to form cations, and non-metals gain electrons to form anions.
- D. Both metals and non-metals share electrons.
Answer: C. Metals lose electrons to form cations, and non-metals gain electrons to form anions. — Metals tend to lose valence electrons to achieve a stable noble gas configuration, forming positively charged ions (cations). Non-metals tend to gain electrons to achieve a stable configuration, forming negatively charged ions (anions).
MCQ 14. The naturally occurring compounds of metals, along with impurities, are called:
- A. Ores
- B. Minerals
- C. Slag
- D. Alloys
Answer: B. Minerals — Minerals are naturally occurring substances from which metals can be extracted. Ores are specific minerals from which metals can be profitably extracted.
MCQ 15. Which of the following methods is used for preventing the rusting of iron by applying a protective coating of a more reactive metal?
- A. Anodising
- B. Alloying
- C. Galvanisation
- D. Chromate plating
Answer: C. Galvanisation — Galvanisation involves coating iron with a layer of zinc. Zinc is more reactive than iron, so it corrodes preferentially, protecting the iron even if the coating is scratched. Anodising is for aluminium, alloying creates new materials, and chromate plating uses chromium.
MCQ 16. Bronze, an alloy of copper and tin, is preferred over pure copper for making statues and bells primarily because:
- A. It is more ductile than copper.
- B. It is a better conductor of electricity than copper.
- C. It is harder and more resistant to corrosion than pure copper.
- D. It has a lower melting point, making casting easier.
Answer: C. It is harder and more resistant to corrosion than pure copper. — Alloys like bronze are generally harder, stronger, and more resistant to corrosion than their constituent pure metals, making them suitable for applications like statues and bells. Pure copper is more ductile and a better conductor of electricity.
MCQ 17. Which of the following metals is a liquid at room temperature?
- A. Iron
- B. Mercury
- C. Sodium
- D. Aluminium
Answer: B. Mercury — Mercury is the only metal that is a liquid at room temperature (around 25°C).
MCQ 18. When carbon dioxide is dissolved in water, the resulting solution will:
- A. Turn red litmus blue.
- B. Have a neutral pH.
- C. Turn blue litmus red.
- D. Not affect litmus paper.
Answer: C. Turn blue litmus red. — Carbon dioxide is an oxide of a non-metal, and non-metal oxides are generally acidic. When dissolved in water, it forms carbonic acid, which will turn blue litmus paper red.
MCQ 19. Metals low in the reactivity series can be extracted by:
- A. Electrolytic reduction
- B. Heating their oxides alone
- C. Reduction with carbon
- D. Displacement by a more reactive metal
Answer: B. Heating their oxides alone — Metals low in the reactivity series, like mercury and copper, are very unreactive. Their oxides can often be reduced to metal simply by heating them alone (e.g., HgO → Hg + O2, Cu2S → Cu + SO2 after roasting).
MCQ 20. An iron nail is dipped in an aqueous solution of copper sulphate. Which of the following statements is true regarding the observation?
- A. The solution remains blue, and no change is observed on the iron nail.
- B. The solution turns green, and a reddish-brown layer forms on the iron nail.
- C. The solution turns colourless, and the iron nail dissolves completely.
- D. The solution remains blue, but the iron nail starts to rust rapidly.
Answer: B. The solution turns green, and a reddish-brown layer forms on the iron nail. — Iron is more reactive than copper. It displaces copper from copper sulphate solution, forming ferrous sulphate (green solution) and depositing reddish-brown copper on the iron nail.
How to Use These Solutions
Attempt each question yourself first and only then compare with the worked answer. Marks in the CBSE board exam are awarded for the METHOD as much as the final result, so reproduce the steps rather than memorising the last line. Where a solution states a law, a formula or a definition, learn that wording — examiners look for it.
Related practice for this chapter: chapter MCQs, previous-year questions, revision notes and sample papers.