CBSE Class 10 Science Chemistry
Metals and Non-Metals Important Questions and Answers for Class 10 CBSE
NCERT + Board Exam + Exemplar + Olympiad level question bank covering physical and chemical properties, reactivity series, ionic compounds, ores, minerals, extraction of metals and corrosion.
Short Introduction
The chapter Metals and Non-Metals explains how metals and non-metals differ in their physical and chemical properties. It also covers the reactivity series, formation and properties of ionic compounds, extraction of metals from ores, corrosion and prevention of corrosion. This chapter is very important for CBSE board exams because it includes reasoning questions, chemical equations, activity-based questions and application-based questions.
Chapter Overview
Metals
Metals are generally lustrous, malleable, ductile, sonorous and good conductors of heat and electricity.
Non-Metals
Non-metals are generally dull, brittle, non-sonorous and poor conductors, except graphite.
Reactivity Series
The reactivity series arranges metals in decreasing order of chemical reactivity.
Ionic Compounds
Ionic compounds are formed by transfer of electrons between metals and non-metals.
Ores and Minerals
Metals are found in nature as minerals and ores. Ores are minerals from which metals can be extracted profitably.
Extraction of Metals
Extraction depends on the position of the metal in the reactivity series.
Important Keywords
Important Very Short Answer Questions
Q1. What are metals?
Answer: Metals are elements that generally lose electrons to form positive ions. They are usually hard, lustrous, malleable, ductile and good conductors.
Q2. What are non-metals?
Answer: Non-metals are elements that generally gain or share electrons. They are usually dull, brittle and poor conductors of heat and electricity.
Q3. Why are metals called electropositive elements?
Answer: Metals are called electropositive because they lose electrons easily and form positive ions or cations.
Q4. What is malleability?
Answer: The property of metals by which they can be beaten into thin sheets is called malleability.
Q5. What is ductility?
Answer: The property of metals by which they can be drawn into thin wires is called ductility.
Q6. Name one non-metal that conducts electricity.
Answer: Graphite.
Q7. Name one metal that is liquid at room temperature.
Answer: Mercury.
Q8. Name one non-metal that is liquid at room temperature.
Answer: Bromine.
Q9. What is an ionic compound?
Answer: A compound formed by transfer of electrons from a metal to a non-metal is called an ionic compound.
Q10. What is an ore?
Answer: An ore is a mineral from which a metal can be extracted profitably and conveniently.
Q11. What is gangue?
Answer: The unwanted impurities such as sand, soil and rocky material present in an ore are called gangue.
Q12. What is corrosion?
Answer: The slow destruction of a metal due to the action of air, moisture or chemicals is called corrosion.
Q13. What is galvanisation?
Answer: The process of coating iron or steel with a thin layer of zinc to prevent rusting is called galvanisation.
Q14. Name two amphoteric oxides.
Answer: Aluminium oxide, Al2O3, and zinc oxide, ZnO.
Q15. Which metal is best conductor of electricity?
Answer: Silver is the best conductor of electricity.
Short Answer Questions
Q1. Write four physical properties of metals.
Answer:
- Metals are generally hard and lustrous.
- Metals are malleable and ductile.
- Metals are good conductors of heat and electricity.
- Metals are sonorous, meaning they produce sound when struck.
Q2. Write four physical properties of non-metals.
Answer:
- Non-metals are generally dull in appearance.
- They are brittle and non-ductile.
- They are poor conductors of heat and electricity, except graphite.
- They are non-sonorous.
Q3. Why do metals form positive ions?
Answer: Metals have 1, 2 or 3 valence electrons. They lose these electrons easily to attain a stable electronic configuration. Therefore, they form positive ions called cations.
Na → Na+ + e−
Q4. Why do non-metals form negative ions?
Answer: Non-metals have 5, 6 or 7 valence electrons. They gain electrons to complete their octet and form negative ions called anions.
Cl + e− → Cl−
Q5. What happens when metals react with oxygen?
Answer: Metals react with oxygen to form metal oxides. Most metal oxides are basic in nature.
2Cu + O2 → 2CuO
4Al + 3O2 → 2Al2O3
Q6. What happens when non-metals react with oxygen?
Answer: Non-metals react with oxygen to form non-metal oxides. These oxides are generally acidic in nature.
C + O2 → CO2
S + O2 → SO2
Q7. What are amphoteric oxides? Give equations.
Answer: Oxides that react with both acids and bases to form salt and water are called amphoteric oxides.
Al2O3 + 6HCl → 2AlCl3 + 3H2O
Al2O3 + 2NaOH → 2NaAlO2 + H2O
Q8. What happens when metals react with water?
Answer: Metals react with water to form metal hydroxide or metal oxide and hydrogen gas. The reaction depends on the reactivity of the metal.
2Na + 2H2O → 2NaOH + H2
Ca + 2H2O → Ca(OH)2 + H2
Mg + H2O steam → MgO + H2
Q9. What happens when metals react with dilute acids?
Answer: Metals above hydrogen in the reactivity series react with dilute acids to form salt and hydrogen gas.
Zn + 2HCl → ZnCl2 + H2
Mg + 2HCl → MgCl2 + H2
Q10. Why do copper and silver not react with dilute hydrochloric acid?
Answer: Copper and silver are less reactive than hydrogen. They cannot displace hydrogen from dilute hydrochloric acid, so they do not react with it.
Q11. What happens when metals react with solutions of other metal salts?
Answer: A more reactive metal displaces a less reactive metal from its salt solution.
Fe + CuSO4 → FeSO4 + Cu
Iron is more reactive than copper, so it displaces copper from copper sulphate solution.
Q12. What happens when some metals react with bases?
Answer: Some metals such as aluminium and zinc react with strong bases to form complex salts and hydrogen gas.
Zn + 2NaOH → Na2ZnO2 + H2
2Al + 2NaOH + 2H2O → 2NaAlO2 + 3H2
Q13. Do non-metals react with water?
Answer: Non-metals generally do not react with water. Some non-metals are stored under water because they are highly reactive with air. For example, phosphorus is stored under water to prevent its reaction with oxygen.
Q14. How do non-metal oxides react with bases?
Answer: Non-metal oxides are acidic in nature. They react with bases to form salt and water.
CO2 + 2NaOH → Na2CO3 + H2O
SO2 + 2NaOH → Na2SO3 + H2O
Long Answer Questions
Q1. Explain the chemical properties of metals with suitable equations.
Answer: Important chemical properties of metals are:
- Reaction with oxygen: Metals form metal oxides. Most metal oxides are basic.
2Mg + O2 → 2MgO
- Reaction with water: Reactive metals form metal hydroxide and hydrogen gas.
2Na + 2H2O → 2NaOH + H2
- Reaction with dilute acids: Metals above hydrogen form salt and hydrogen gas.
Zn + 2HCl → ZnCl2 + H2
- Reaction with salt solutions: A more reactive metal displaces a less reactive metal from its salt solution.
Fe + CuSO4 → FeSO4 + Cu
- Reaction with bases: Aluminium and zinc react with strong bases to produce hydrogen gas.
Zn + 2NaOH → Na2ZnO2 + H2
Q2. Explain the chemical properties of non-metals with suitable equations.
Answer: Important chemical properties of non-metals are:
- Reaction with oxygen: Non-metals form acidic or neutral oxides.
C + O2 → CO2
S + O2 → SO2
- Reaction with water: Non-metals generally do not react with water.
- Reaction with bases: Non-metal oxides react with bases to form salt and water.
CO2 + 2NaOH → Na2CO3 + H2O
- Reaction with metals: Non-metals react with metals to form ionic compounds.
2Na + Cl2 → 2NaCl
Q3. Describe the formation of sodium chloride as an ionic compound.
Answer:
- Sodium has electronic configuration 2,8,1. It loses one electron to form Na+.
- Chlorine has electronic configuration 2,8,7. It gains one electron to form Cl−.
- The oppositely charged Na+ and Cl− ions attract each other strongly.
- This strong electrostatic force of attraction forms an ionic bond.
Na → Na+ + e−
Cl + e− → Cl−
Na+ + Cl− → NaCl
Q4. Write the properties of ionic compounds.
Answer: Ionic compounds have the following properties:
- They are usually crystalline solids.
- They are hard and brittle.
- They have high melting and boiling points due to strong electrostatic forces.
- They are generally soluble in water but insoluble in organic solvents like kerosene and petrol.
- They conduct electricity in molten state or aqueous solution because ions are free to move.
- They do not conduct electricity in solid state because ions are fixed in position.
Q5. What is reactivity series? Explain its importance.
Answer: The reactivity series is a list of metals arranged in decreasing order of their reactivity.
Importance:
- It helps to compare the reactivity of metals.
- It helps to predict displacement reactions.
- It helps to decide the method of extraction of metals.
- It tells which metals can displace hydrogen from acids.
Q6. Explain how metals exist in nature.
Answer:
- Very unreactive metals such as gold, silver and platinum occur in free state because they do not react easily.
- Reactive metals occur in combined state as oxides, sulphides, carbonates, chlorides or other compounds.
- Some metals occur as minerals, but only those minerals from which metals can be extracted profitably are called ores.
- For example, aluminium is found as bauxite and iron is found as haematite.
Q7. Explain the main steps involved in extraction of metals from ores.
Answer: The extraction of metals from ores involves the following steps:
- Concentration of ore: Removal of gangue or unwanted impurities from the ore.
- Conversion into oxide: Sulphide ores are converted into oxides by roasting. Carbonate ores are converted into oxides by calcination.
- Reduction: Metal oxides are reduced to free metals using reducing agents like carbon or by electrolysis.
- Refining: Impure metal is purified. Electrolytic refining is commonly used for copper, zinc and silver.
Q8. Differentiate between roasting and calcination.
| Roasting | Calcination |
|---|---|
| It is used for sulphide ores. | It is used for carbonate ores. |
| Ore is heated strongly in the presence of excess air. | Ore is heated strongly in limited or no air. |
| Example: 2ZnS + 3O2 → 2ZnO + 2SO2 | Example: ZnCO3 → ZnO + CO2 |
Q9. Explain electrolytic refining of copper.
Answer: In electrolytic refining of copper:
- The impure copper is made the anode.
- A thin strip of pure copper is made the cathode.
- Copper sulphate solution acidified with sulphuric acid is used as electrolyte.
- On passing electric current, pure copper deposits on the cathode.
- Impurities settle below the anode as anode mud.
Important Tables for Quick Learning
Physical Properties of Metals and Non-Metals
| Property | Metals | Non-Metals |
|---|---|---|
| Lustre | Generally lustrous | Generally dull, except iodine |
| Malleability | Malleable | Non-malleable |
| Ductility | Ductile | Non-ductile |
| Conductivity | Good conductors | Poor conductors, except graphite |
| Sound | Sonorous | Non-sonorous |
| State | Mostly solids, except mercury | Solids, liquids or gases |
Extraction Based on Reactivity
| Position in Reactivity Series | Examples | Method of Extraction |
|---|---|---|
| Highly reactive metals | K, Na, Ca, Mg, Al | Electrolytic reduction of molten compounds |
| Moderately reactive metals | Zn, Fe, Pb | Conversion into oxide followed by reduction using carbon |
| Low reactive metals | Cu, Hg, Ag, Au | Simple heating or found in native state |
Case-Study Based Questions
Case Study 1: Displacement Reaction
A student places an iron nail in blue copper sulphate solution. After some time, the blue colour fades and a reddish-brown deposit appears on the iron nail.
Q1. Why does the blue colour of copper sulphate fade?
Answer: Iron displaces copper from copper sulphate solution and forms iron sulphate, which is pale green.
Q2. Write the chemical equation.
Fe + CuSO4 → FeSO4 + Cu
Q3. What does this activity prove?
Answer: It proves that iron is more reactive than copper.
Case Study 2: Formation of Ionic Compound
Sodium reacts with chlorine to form sodium chloride. Sodium loses one electron and chlorine gains one electron.
Q1. Which ion is formed by sodium?
Answer: Sodium forms Na+ ion.
Q2. Which ion is formed by chlorine?
Answer: Chlorine forms Cl− ion.
Q3. Why is sodium chloride an ionic compound?
Answer: It is formed by transfer of electrons and contains oppositely charged ions held together by strong electrostatic forces.
Case Study 3: Extraction of Metals
A metal ore contains zinc carbonate. The ore is first converted into zinc oxide and then reduced to zinc.
Q1. What is the process of converting zinc carbonate into zinc oxide called?
Answer: Calcination.
Q2. Write the equation for calcination of zinc carbonate.
ZnCO3 → ZnO + CO2
Q3. How is zinc oxide reduced to zinc?
Answer: Zinc oxide is reduced by carbon.
ZnO + C → Zn + CO
Case Study 4: Corrosion
Iron articles develop a reddish-brown flaky layer when exposed to moist air for a long time.
Q1. What is this reddish-brown layer called?
Answer: Rust.
Q2. What conditions are necessary for rusting?
Answer: Air or oxygen and moisture are necessary for rusting.
Q3. Give two methods to prevent rusting.
Answer: Painting, oiling, greasing, galvanisation and alloying can prevent rusting.
Critical Thinking Questions
Q1. Why is sodium stored in kerosene?
Answer: Sodium is highly reactive and reacts vigorously with air and water. It is stored in kerosene to prevent contact with air and moisture.
Q2. Why does calcium float on water during reaction?
Answer: Calcium reacts with water to produce hydrogen gas. The bubbles of hydrogen gas stick to the surface of calcium and make it float.
Q3. Why does aluminium not corrode easily even though it is reactive?
Answer: Aluminium forms a thin protective layer of aluminium oxide on its surface. This prevents further corrosion.
Q4. Why does magnesium ribbon need to be cleaned before burning?
Answer: Magnesium ribbon has a layer of magnesium oxide on its surface. It is cleaned to remove this layer so that magnesium burns easily.
Q5. Why do ionic compounds have high melting points?
Answer: Ionic compounds have strong electrostatic forces of attraction between oppositely charged ions. A large amount of energy is required to break these forces.
Q6. Why can molten sodium chloride conduct electricity but solid sodium chloride cannot?
Answer: In solid sodium chloride, ions are fixed and cannot move. In molten sodium chloride, ions are free to move and conduct electricity.
Q7. Why can iron displace copper from copper sulphate but copper cannot displace iron from iron sulphate?
Answer: Iron is more reactive than copper, so it can displace copper from its salt solution. Copper is less reactive than iron, so it cannot displace iron.
Q8. Why are gold and platinum found in free state in nature?
Answer: Gold and platinum are very less reactive metals. They do not easily combine with oxygen, water or other elements, so they occur in free state.
Q9. Why are highly reactive metals extracted by electrolysis?
Answer: Highly reactive metals have strong affinity for oxygen and cannot be reduced by carbon. Therefore, they are extracted by electrolytic reduction.
Q10. Why is carbon not used to reduce aluminium oxide?
Answer: Aluminium is highly reactive and has strong affinity for oxygen. Carbon cannot reduce aluminium oxide effectively, so aluminium is extracted by electrolysis.
Previous Year Board Exam Pattern Questions
Q1. Give reasons: Ionic compounds are generally hard and have high melting points.
Answer: Ionic compounds have strong electrostatic forces of attraction between oppositely charged ions. A large amount of energy is needed to break these forces. Therefore, they are hard and have high melting points.
Q2. A metal X reacts with dilute hydrochloric acid to produce hydrogen gas, but copper does not. What can you say about X?
Answer: Metal X is more reactive than hydrogen and can displace hydrogen from dilute hydrochloric acid. Copper is less reactive than hydrogen and cannot displace hydrogen.
Q3. Write two differences between metals and non-metals based on their chemical properties.
Answer:
- Metals lose electrons to form positive ions, while non-metals gain electrons to form negative ions.
- Metal oxides are generally basic, while non-metal oxides are generally acidic.
Q4. What is thermite reaction? Write its use.
Answer: The reaction between aluminium and iron oxide is called thermite reaction.
Fe2O3 + 2Al → 2Fe + Al2O3 + heat
It is used for joining railway tracks and repairing cracked machine parts.
Q5. Explain why copper vessels become green when exposed to moist air.
Answer: Copper reacts with carbon dioxide, oxygen and moisture in air to form a green coating of basic copper carbonate.
Q6. What is an alloy? Give one example.
Answer: An alloy is a homogeneous mixture of two or more metals or a metal and a non-metal. Example: Brass is an alloy of copper and zinc.
Olympiad Level Questions
Q1. A metal M forms M2+ ion. It reacts with hydrochloric acid and displaces hydrogen. What can be inferred?
Answer: Metal M loses two electrons to form M2+. Since it displaces hydrogen from hydrochloric acid, it is placed above hydrogen in the reactivity series.
Q2. A solid compound has high melting point and conducts electricity only in molten state. What type of compound is it?
Answer: It is an ionic compound because ionic compounds conduct electricity only when molten or dissolved in water.
Q3. Metal A displaces metal B from its salt solution. Metal C displaces metal A from its salt solution. Arrange A, B and C in decreasing order of reactivity.
Answer: Since A displaces B, A is more reactive than B. Since C displaces A, C is more reactive than A. Therefore, order is C > A > B.
Q4. Why is graphite a non-metal but still used as an electrode?
Answer: Graphite has free electrons that can move and conduct electricity. Therefore, it is used as an electrode even though it is a non-metal.
Q5. A metal oxide reacts with both acid and base. What is the nature of the oxide?
Answer: The oxide is amphoteric in nature. Examples include Al2O3 and ZnO.
Q6. Why is the extraction of sodium different from the extraction of zinc?
Answer: Sodium is highly reactive and is extracted by electrolysis of molten sodium chloride. Zinc is moderately reactive and can be extracted by reduction of zinc oxide using carbon.
Assertion-Reason Questions
Choose the correct option:
A. Both Assertion and Reason are true and Reason is the correct explanation.
B. Both Assertion and Reason are true but Reason is not the correct explanation.
C. Assertion is true but Reason is false.
D. Assertion is false but Reason is true.
Q1. Assertion: Metals are electropositive elements. Reason: Metals lose electrons easily to form cations.
Answer: A. Both Assertion and Reason are true and Reason is the correct explanation.
Q2. Assertion: Ionic compounds conduct electricity in solid state. Reason: Ions are free to move in solid state.
Answer: D. Assertion is false but Reason is false in concept. Correct statement: Ionic compounds do not conduct electricity in solid state because ions are fixed.
Q3. Assertion: Gold occurs in free state in nature. Reason: Gold is very less reactive.
Answer: A. Both Assertion and Reason are true and Reason is the correct explanation.
Q4. Assertion: Aluminium is used in thermite welding. Reason: Aluminium is a strong reducing agent.
Answer: A. Both Assertion and Reason are true and Reason is the correct explanation.
Q5. Assertion: Zinc oxide is amphoteric. Reason: Zinc oxide reacts with both acids and bases.
Answer: A. Both Assertion and Reason are true and Reason is the correct explanation.
Quick Revision Box
Most Reactive Metal
Potassium
Best Conductor
Silver
Liquid Metal
Mercury
Liquid Non-Metal
Bromine
Non-Metal Conductor
Graphite
Amphoteric Oxides
Al2O3, ZnO
Rust Formula
Fe2O3 · xH2O
Ore of Aluminium
Bauxite
Ore of Iron
Haematite
Exam Tips
Interactive Practice Zone
Reactivity Series Checker
Select two metals and check which one is more reactive.
Mini Quiz
Which method is used to extract highly reactive metals like sodium and aluminium?
FAQ Section
Why are metals called electropositive?
Metals are called electropositive because they lose electrons easily and form positive ions.
Why are ionic compounds hard and have high melting points?
Ionic compounds have strong electrostatic forces of attraction between oppositely charged ions. Therefore, they are hard and have high melting points.
Why does sodium react vigorously with water?
Sodium is a highly reactive metal. It reacts with water to form sodium hydroxide and hydrogen gas, releasing a large amount of heat.
What is the difference between mineral and ore?
A mineral is a naturally occurring compound of a metal. An ore is a mineral from which the metal can be extracted profitably and conveniently.
What is the difference between roasting and calcination?
Roasting is heating sulphide ore in excess air, while calcination is heating carbonate ore in limited or no air.
Why is aluminium resistant to corrosion?
Aluminium forms a thin protective layer of aluminium oxide on its surface, which prevents further corrosion.
What are amphoteric oxides?
Amphoteric oxides react with both acids and bases to form salt and water. Examples include aluminium oxide and zinc oxide.
Why is graphite used as an electrode?
Graphite conducts electricity due to the presence of free electrons, so it is used as an electrode.
Final Conclusion
Metals and Non-Metals is a scoring chapter in Class 10 Science Chemistry. Students should focus on properties, exceptions, reactions, reactivity series, ionic compounds, extraction of metals and corrosion. Practising chemical equations, reasoning questions, case-study questions and NCERT-based concepts will help students perform strongly in CBSE board exams and competitive-level tests.
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