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Metals and Non-Metals Class 10 Extra Questions and Answers provide additional practice on important topics from the chapter. These questions cover physical and chemical properties, reactivity series, ionic compounds, extraction of metals, corrosion, and alloys.
Metals and Non Metals Class 10 Extra Questions and Answers
Important Questions
Q. Explain why metals like copper and aluminium are used for making cooking vessels.
Answer: Copper and aluminium are good conductors of heat. They spread heat quickly and evenly. They also have high melting points, so they do not melt while cooking.
Q. Why are school bells made of metals? Relate your answer to the property of metals.
Answer: Metals are sonorous. This means they produce a ringing sound when struck. That is why school bells are made of metals.
Q. Why is sodium kept under kerosene oil?
Answer: Sodium is very reactive. It reacts quickly with oxygen and moisture in air. To stop this reaction, sodium is stored under kerosene oil.
Q. Write balanced equations for the reaction of copper and aluminium with oxygen.
Answer:
Copper + Oxygen → Copper(II) oxide
- 2Cu + O₂ → 2CuO
Aluminium + Oxygen → Aluminium oxide
- 4Al + 3O₂ → 2Al₂O₃
Q. Why are sodium and potassium stored in kerosene oil?
Answer: Sodium and potassium are highly reactive metals. They react strongly with air and moisture. To prevent this, they are stored under kerosene oil.
Q. What are amphoteric oxides? Give two examples with equations.
Answer: Amphoteric oxides react with both acids and bases. Examples:
Aluminium oxide + Hydrochloric acid → Aluminium chloride + Water
- Al₂O₃ + 6HCl → 2AlCl₃ + 3H₂O
Aluminium oxide + Sodium hydroxide → Sodium aluminate + Water
- Al₂O₃ + 2NaOH → 2NaAlO₂ + H₂O
Q. Write the balanced chemical equation for the reaction between iron and copper sulphate solution.
Answer:
Iron + Copper sulphate → Iron sulphate + Copper
Fe + CuSO₄ → FeSO₄ + Cu
Q. Define displacement reaction with one suitable example.
Answer: A displacement reaction is when a more reactive metal displaces a less reactive metal from its compound. Example:
Zinc + Copper sulphate → Zinc sulphate + Copper
Zn + CuSO₄ → ZnSO₄ + Cu
Q. What is the reactivity series of metals? Why is it useful?
Answer: The reactivity series is a list of metals arranged in decreasing order of reactivity. It is useful to predict how metals react with oxygen, water, acids, and salt solutions.
Q. Explain why metals tend to lose electrons while non‑metals tend to gain electrons.
Answer: Metals have few electrons in their outer shell. They lose them to get a stable configuration. Non‑metals have more electrons in their outer shell. They gain electrons to complete their octet.
Q. Write the electronic configuration of sodium and chlorine. Show how they form sodium chloride.
Answer: Sodium (11): 2,8,1. Chlorine (17): 2,8,7. Sodium loses 1 electron → Na⁺. Chlorine gains 1 electron → Cl⁻. Together they form NaCl by ionic bond.
Q. Define ionic compounds. Give two examples.
Answer: Ionic compounds are formed by transfer of electrons from metals to non‑metals. They contain oppositely charged ions. Examples: NaCl, MgCl₂.
Q. Define minerals and ores. Give one example of each.
Answer: Minerals are natural substances found in earth’s crust. Ores are minerals from which metals can be profitably extracted. Example: Bauxite is an ore of aluminium.
Q. Why are oxides the most common ores of metals?
Answer: Oxygen is very reactive and abundant on earth. So metals often combine with oxygen to form oxides.
Q. Write the equations for extraction of mercury from cinnabar and copper from copper sulphide.
Answer:
Mercury extraction:
- 2HgS + 3O₂ → 2HgO + 2SO₂
- 2HgO → 2Hg + O₂
Copper extraction:
- 2Cu₂S + 3O₂ → 2Cu₂O + 2SO₂
- 2Cu₂O + Cu₂S → 6Cu + SO₂
Q. Define corrosion. Give examples of corrosion of silver, copper, and iron.
Answer: Corrosion is the slow eating away of metals by air, moisture, or chemicals. Silver → black coating of silver sulphide. Copper → green coating of basic copper carbonate. Iron → brown flaky rust.
Q. Write the chemical name of the green coating formed on copper.
Answer: The green coating is basic copper carbonate.
Q. What is rust chemically?
Answer: Rust is hydrated iron(III) oxide, written as Fe₂O₃·xH₂O.
Why/Reason-Based
Q. Why does sodium metal cut easily with a knife while iron cannot?
Answer: Sodium is a very soft metal. It can be cut easily with a knife. Iron is hard, so it cannot be cut with a knife.
Q. Why do wires used in electrical circuits have a coating of PVC or rubber?
Answer: Metals conduct electricity. PVC or rubber does not conduct electricity. The coating prevents electric shocks and makes wires safe to handle.
Q. Why are gold and silver considered the most malleable metals?
Answer: Gold and silver can be beaten into very thin sheets without breaking. This property is called malleability. That is why they are considered the most malleable metals.
Q. Why does magnesium burn with a dazzling white flame while copper does not burn but forms a black coating?
Answer: Magnesium is more reactive, so it burns with a bright white flame. Copper is less reactive. It does not burn but reacts with oxygen to form black copper oxide.
Q. Why does calcium float on water during its reaction?
Answer: When calcium reacts with water, bubbles of hydrogen gas stick to its surface. These bubbles make calcium float.
Q. Why does hydrogen gas not evolve when metals react with nitric acid?
Answer: Nitric acid is a strong oxidising agent. It oxidises the hydrogen gas formed into water. That is why hydrogen is not seen.
Q. Why does copper not displace iron from iron sulphate solution?
Answer: Copper is less reactive than iron. A less reactive metal cannot displace a more reactive metal from its compound.
Q. Why is iron able to displace copper from copper sulphate solution?
Answer: Iron is more reactive than copper. A more reactive metal can displace a less reactive metal from its compound.
Q. Why are displacement reactions better evidence for reactivity of metals compared to burning in air?
Answer: Burning in air does not show clear differences for all metals. Displacement reactions clearly show which metal is more reactive, because one metal replaces another from its compound.
Q. Why do noble gases show little chemical activity?
Answer: Noble gases have completely filled outer shells. Their configuration is stable. So they do not react easily.
Q. Why does sodium form Na⁺ ion while chlorine forms Cl⁻ ion?
Answer: Sodium has one electron in its outer shell. It loses this electron to form Na⁺. Chlorine has seven electrons in its outer shell. It gains one electron to form Cl⁻.
Q. Why are ionic compounds generally hard and brittle?
Answer: In ionic compounds, positive and negative ions are held together by strong forces. This makes them hard. When pressure is applied, they break into pieces, so
they are brittle.
Q. Why are metals like gold and silver found in free state in nature?
Answer: Gold and silver are very less reactive. They do not combine easily with oxygen or other elements. So they are found in free state.
Q. Why is roasting used for sulphide ores but calcination for carbonate ores?
Answer: Sulphide ores are heated in air (roasting) to form oxides. Carbonate ores are heated in limited air (calcination) to form oxides. This makes reduction easier.
Q. Why can highly reactive metals like sodium and potassium not be reduced by carbon?
Answer: Sodium and potassium have more affinity for oxygen than carbon. So carbon cannot remove oxygen from their oxides.
Q. Why do iron nails rust only when exposed to both air and water?
Answer: Rusting needs both oxygen (from air) and moisture (water). Without either one, rusting does not occur.
Q. Why does galvanised iron remain protected even if the zinc coating is broken?
Answer: Zinc is more reactive than iron. Even if the coating breaks, zinc reacts first and protects iron from rusting.
Q. Why is pure gold not used for making ornaments?
Answer: Pure gold is very soft. It bends and stretches easily. To make it hard and strong, it is mixed with copper or silver before making ornaments.
Application-Based
Q. A blacksmith beats a piece of iron into a thin sheet. Which property of metals does this activity demonstrate?
Answer: This shows the property of malleability. Metals can be hammered into thin sheets without breaking.
Q. Aluminium foil is used for wrapping food items. Which property of aluminium makes it suitable for this purpose?
Answer: Aluminium is malleable. It can be beaten into very thin sheets, so it is used as foil for wrapping food.
Q. Why do cooking vessels made of copper or aluminium not melt while cooking, even though they are heated strongly?
Answer: Copper and aluminium have high melting points. The heat used in cooking is not enough to melt them.
Q. Aluminium articles are anodised before use. Explain the purpose of anodising.
Answer: Anodising makes a thick oxide layer on aluminium. This layer protects aluminium from corrosion and gives it a shiny finish.
Q. Why do cooking vessels made of aluminium not corrode easily in air?
Answer: Aluminium forms a thin oxide layer on its surface. This layer protects it from further corrosion.
Q. A student observed bubbles when zinc was placed in dilute HCl. Identify the gas evolved and write the reaction.
Answer: The gas evolved is hydrogen.
Zinc + Hydrochloric acid → Zinc chloride + Hydrogen
- Zn + 2HCl → ZnCl₂ + H₂
Q. A student dipped an iron nail in copper sulphate solution. After some time, the nail turned brownish and the solution became green. Explain the changes observed.
Answer: Iron displaced copper from copper sulphate. Copper deposited on the nail (brownish). Iron sulphate formed in solution (green).
Q. How can you use displacement reactions to arrange metals in decreasing order of reactivity?
Answer: By testing which metal displaces another from its salt solution. The more reactive metal will replace the less reactive one. This helps arrange metals in order of reactivity.
Q. Why is hydrogen included in the reactivity series of metals even though it is a non‑metal?
Answer: Hydrogen behaves like metals in reactions with acids. It is displaced by more reactive metals from acids. So it is included in the series for comparison.
Q. Aluminium oxide reacts with both acids and bases. What does this show about its nature? Write equations.
Answer: Aluminium oxide is amphoteric. It reacts with both acids and bases.
- Al₂O₃ + 6HCl → 2AlCl₃ + 3H₂O
- Al₂O₃ + 2NaOH → 2NaAlO₂ + H₂O
Q. Why are ionic compounds soluble in water but not in petrol or kerosene?
Answer: Water is polar and can separate ions. Petrol and kerosene are non‑polar, so they cannot dissolve ionic compounds.
Q. Why do ionic compounds conduct electricity in molten state but not in solid state?
Answer: In solid state, ions cannot move. In molten state, ions move freely and carry electric current.
Q. Explain the thermit reaction. How is it applied in joining railway tracks?
Answer: In thermit reaction, aluminium reduces iron oxide to molten iron.
- Fe₂O₃ + 2Al → 2Fe + Al₂O₃ + heat
The molten iron produced is used to weld and join railway tracks.
Q. Why is aluminium used as a reducing agent in metallurgy?
Answer: Aluminium is highly reactive. It can displace less reactive metals from their oxides, producing molten metal.
Q. How does anodising improve the resistance of aluminium articles?
Answer: Anodising makes a thick oxide layer. This layer protects aluminium from rusting and corrosion.
Q. Explain why stainless steel is preferred over pure iron for making utensils.
Answer: Pure iron is soft and rusts easily. Stainless steel (iron mixed with nickel and chromium) is hard, strong, and does not rust.
Q. Why are bridges and ships painted regularly?
Answer: Paint prevents contact of iron with air and water. This stops rusting and corrosion.
Q. How does alloying improve the properties of metals? Give one example.
Answer: Alloying changes hardness, strength, and resistance to rust. Example: Iron mixed with nickel and chromium forms stainless steel, which is strong and rust‑free.
Case-Based
Q. Case Study: A student sets up an experiment to test the conductivity of different metals by connecting them in a circuit with a bulb. He observes that the bulb glows brightly with copper and aluminium, but dimly with lead.
Answer:
- The property being tested is electrical conductivity of metals.
- The bulb glows differently because copper and aluminium are good conductors, while lead is a poor conductor.
- The best conductors of heat and electricity are silver and copper.
Q. Case Study: A student tested metals with dilute HCl. He observed:
- Magnesium reacted vigorously with high temperature rise.
- Aluminium and zinc reacted moderately.
- Iron reacted slowly.
- Copper showed no reaction.
Answer:
- Decreasing order of reactivity: Magnesium > Aluminium > Zinc > Iron > Copper.
- The property being tested is reactivity of metals with acids.
- Copper did not react because it is less reactive than hydrogen.
Q. Case Study: A student placed copper wire in iron sulphate solution and iron nail in copper sulphate solution. After 20 minutes, he observed no change in the first test tube but a reddish‑brown deposit in the second.
Answer:
- The reaction occurred in the test tube with iron nail in copper sulphate solution.
- The reddish‑brown deposit indicates copper metal formed.
- Iron is more reactive than copper, so iron displaced copper.
Q. Case Study: A student dissolved sodium chloride in water and tested its conductivity. The bulb glowed.
Answer:
- This shows that NaCl solution contains ions which conduct electricity.
- Solid NaCl does not conduct because ions cannot move in solid state.
- NaCl has ionic bonding (between Na⁺ and Cl⁻).
Q. Case Study: A student studied zinc ores. He found that zinc sulphide was converted to zinc oxide by roasting, while zinc carbonate was converted to zinc oxide by calcination.
Answer: Equations:
- Roasting: 2ZnS + 3O₂ → 2ZnO + 2SO₂
- Calcination: ZnCO₃ → ZnO + CO₂
It is easier to reduce oxides because oxygen can be removed easily. The common reducing agent used is carbon (coke).
Q. Case Study: A student placed iron nails in three test tubes:
- Tube A: water + air → nails rusted
- Tube B: boiled water + oil → no rust
- Tube C: dry air + CaCl₂ → no rust
Answer:
- Rusting occurred in Tube A.
- Conditions needed: both air (oxygen) and water (moisture).
- Two methods to prevent rusting: painting/oiling and galvanisation.
Experiment-Based
Q. Describe the experiment where a pin is fixed with wax on a copper wire and the wire is heated. What does this experiment prove about metals?
Answer: When the wire is heated, the pin falls as the wax melts. This shows that metals are good conductors of heat.
Q. Magnesium ribbon and sulphur powder are burnt. Write the equations and state whether the oxides formed are acidic or basic.
Answer:
Magnesium + Oxygen → Magnesium oxide
- 2Mg + O₂ → 2MgO (basic oxide)
Sulphur + Oxygen → Sulphur dioxide
- S + O₂ → SO₂ (acidic oxide)
Q. What conclusion can be drawn from the rusting experiment with iron nails in three test tubes (A: water + air, B: boiled water + oil, C: dry air + CaCl₂)?
Answer: Rusting occurred only in tube A. This proves that both air and water are necessary for rusting.
Q. Describe the experiment of burning metals in air. What conclusions can be drawn about reactivity of metals with oxygen?
Answer: Some metals like sodium burn vigorously, while others like copper only form a coating. This shows that different metals have different reactivities with oxygen.
Q. Iron filings burn vigorously in flame but a piece of iron does not. Explain.
Answer: Iron filings have a large surface area, so they react faster with oxygen. A big piece has less surface area, so it does not burn easily.
Q. Write the equations for the reaction of aluminium and iron with steam.
Answer:
Aluminium + Steam → Aluminium oxide + Hydrogen
- 2Al + 3H₂O → Al₂O₃ + 3H₂
Iron + Steam → Iron oxide + Hydrogen
- 3Fe + 4H₂O → Fe₃O₄ + 4H₂
Q. Describe the experiment with copper wire in iron sulphate solution and iron nail in copper sulphate solution. What conclusion can be drawn?
Answer: Copper wire in iron sulphate shows no change. Iron nail in copper sulphate forms a brown deposit of copper. This proves that iron is more reactive than copper.
Q. Write the balanced equation for the reaction between zinc and iron sulphate solution.
Answer:
Zinc + Iron sulphate → Zinc sulphate + Iron
- Zn + FeSO₄ → ZnSO₄ + Fe
Q. How can displacement reactions be used to confirm the relative reactivity of magnesium and zinc?
Answer: Place magnesium in zinc sulphate solution and zinc in magnesium sulphate solution. The metal that displaces the other is more reactive.
Q. Describe the experiment of testing salts for solubility and conductivity. What conclusions can be drawn?
Answer: Ionic salts dissolve in water but not in petrol or kerosene. Their solutions conduct electricity. This shows that ionic compounds are soluble in water and conduct electricity in solution.
Q. Write the equations for the formation of magnesium chloride from magnesium and chlorine.
Answer:
Magnesium + Chlorine → Magnesium chloride
- Mg + Cl₂ → MgCl₂
Q. What happens when sodium oxide dissolves in water? Write the equation.
Answer: Sodium oxide forms sodium hydroxide, which is an alkali.
- Na₂O + H₂O → 2NaOH
Q. Describe the steps involved in electrolytic refining of copper. What is anode mud?
Answer: In refining, impure copper is made the anode, pure copper is the cathode, and copper sulphate solution is the electrolyte. Pure copper deposits on the cathode. The impurities settle down as anode mud.
Q. Write the electrode reactions for electrolysis of molten sodium chloride.
Answer:
- At cathode: Na⁺ + e⁻ → Na
- At anode: 2Cl⁻ → Cl₂ + 2e⁻
Q. How can displacement reactions be used to extract metals of medium reactivity?
Answer: Highly reactive metals like aluminium can displace medium reactive metals from their oxides. Example: Aluminium displaces manganese from MnO₂.
Q. Describe the experiment with iron nails in three test tubes (A: water + air, B: boiled water + oil, C: dry air + CaCl₂). What conclusion can be drawn?
Answer: Rusting occurred only in tube A. This shows that both air and water are required for rusting.
Q. How can you experimentally show that silver reacts with sulphur in air to form silver sulphide?
Answer: Place silver in air containing sulphur compounds. After some time, a black coating forms. This coating is silver sulphide.
Q. Explain how anhydrous calcium chloride prevents rusting in test tube C.
Answer: Anhydrous calcium chloride absorbs moisture from air. Without moisture, rusting does not occur.
Compare/Differentiate
Q. Differentiate between metals and non‑metals on the basis of:
(i) Malleability
(ii) Conductivity
(iii) Sonority
Answer:
- Metals are malleable (can be hammered into sheets), non‑metals are not.
- Metals conduct heat and electricity, non‑metals are poor conductors.
- Metals are sonorous (produce ringing sound), non‑metals are not.
Q. Compare the properties of diamond and graphite (both allotropes of carbon).
Answer:
| diamond | graphite |
|---|---|
| Diamond is very hard | graphite is soft |
| Diamond does not conduct electricity | graphite conducts electricity |
| Diamond has a 3D rigid structure | graphite has layered structure |
Q. Compare the melting points of gallium/caesium with those of most other metals.
Answer:
- Gallium and caesium have very low melting points.
- Most other metals have high melting points.
Q. Differentiate between the reaction of sodium and magnesium with water.
Answer:
- Sodium reacts violently with cold water, producing hydrogen that catches fire.
- Magnesium does not react with cold water, but reacts slowly with hot water or steam.
Q. Compare the behaviour of copper and magnesium when treated with dilute HCl.
Answer:
- Magnesium reacts vigorously with dilute HCl, producing hydrogen gas.
- Copper does not react with dilute HCl.
Q. Distinguish between basic oxides and amphoteric oxides with examples.
Answer:
- Basic oxides react only with acids. Example: Na₂O.
- Amphoteric oxides react with both acids and bases. Example: Al₂O₃.
Q. Differentiate between the reaction of copper wire in iron sulphate solution and iron nail in copper sulphate solution.
Answer:
- Copper wire in iron sulphate solution shows no reaction.
- Iron nail in copper sulphate solution forms a brown deposit of copper.
Q. Compare the reactivity of potassium and gold based on the reactivity series.
Answer:
- Potassium is highly reactive, placed at the top of the series.
- Gold is least reactive, placed at the bottom of the series.
Q. Distinguish between oxidation and reduction in the displacement reaction of iron with copper sulphate.
Answer:
- Fe + CuSO₄ → FeSO₄ + Cu
Iron is oxidised (loses electrons).
Copper is reduced (gains electrons).
Q. Differentiate between covalent and ionic compounds on the basis of conductivity, melting point, and solubility.
Answer:
- Covalent compounds: poor conductors, low melting points, insoluble in water.
- Ionic compounds: good conductors in molten state, high melting points, soluble in water.
Q. Compare the properties of sodium chloride and graphite.
Answer:
- Sodium chloride: ionic, hard, soluble in water, conducts electricity in molten state.
- Graphite: covalent, soft, insoluble in water, conducts electricity.
Q. Distinguish between basic oxides and amphoteric oxides with examples.
Answer:
- Basic oxides: react only with acids (e.g., CaO).
- Amphoteric oxides: react with both acids and bases (e.g., ZnO).
Q. Differentiate between roasting and calcination with equations.
Answer:
Roasting: heating sulphide ores in air.
- 2ZnS + 3O₂ → 2ZnO + 2SO₂
Calcination: heating carbonate ores in limited air.
- ZnCO₃ → ZnO + CO₂
Q. Compare the extraction methods of metals of low, medium, and high reactivity.
Answer:
- Low reactivity metals: reduced by heating alone (e.g., Hg).
- Medium reactivity metals: reduced by carbon or displacement (e.g., Zn, Fe).
- High reactivity metals: extracted by electrolysis (e.g., Na, Al).
Q. Distinguish between electrolytic reduction and electrolytic refining.
Answer:
- Electrolytic reduction: extraction of metals from compounds using electricity.
- Electrolytic refining: purification of impure metals using electricity.
Q. Differentiate between corrosion of copper and silver.
Answer:
- Copper forms green coating of basic copper carbonate.
- Silver forms black coating of silver sulphide.
Q. Compare the properties of pure iron and stainless steel.
Answer:
- Pure iron: soft, rusts easily.
- Stainless steel: hard, strong, resistant to rust (iron mixed with chromium and nickel).
Q. Distinguish between alloys and pure metals with examples.
Answer:
- Pure metals: contain only one type of metal (e.g., copper, iron).
- Alloys: mixtures of metals or metals with non‑metals (e.g., brass = copper + zinc, stainless steel = iron + chromium + nickel).
Competency-Based
Q. A student observes that iodine (a non‑metal) is lustrous, while graphite (a non‑metal) conducts electricity. What does this tell us about grouping elements only by physical properties?
Answer: It shows that physical properties alone are not enough to classify elements. Some non‑metals like iodine and graphite show metallic properties.
Q. Explain how the properties of metals are related to their uses in daily life (give at least three examples).
Answer:
- Copper and aluminium are good conductors, so they are used in wires and cooking vessels.
- Iron is strong, so it is used in construction.
- Gold and silver are malleable, so they are used in ornaments.
Q. Why is it not possible to classify elements strictly as metals or non‑metals based only on physical properties?
Answer: Because there are exceptions. Example: Iodine is a non‑metal but lustrous, graphite is a non‑metal but conducts electricity.
Q. Explain how the reactivity of metals with oxygen, water, and acids helps us to arrange them in a reactivity series.
Answer: Metals that react strongly with oxygen, water, and acids are placed higher. Metals that react slowly or not at all are placed lower.
Q. Why do metals like silver and gold not react with oxygen even at high temperatures?
Answer: Silver and gold are very less reactive. Their atoms do not combine easily with oxygen, even at high temperatures.
Q. How does the protective oxide layer on aluminium and zinc prevent further oxidation?
Answer: The thin oxide layer covers the surface and stops air and moisture from reaching the metal. This prevents further oxidation.
Q. Explain how displacement reactions help in developing the reactivity series of metals.
Answer: In displacement reactions, a more reactive metal replaces a less reactive one. By observing which metal displaces another, we can arrange metals in order of reactivity.
Q. Why do metals like silver and gold not participate in displacement reactions with common salt solutions?
Answer: Silver and gold are less reactive than most metals. They cannot displace other metals from their salt solutions.
Q. How can displacement reactions be used in industries for extraction of metals?
Answer: Highly reactive metals like aluminium are used to displace less reactive metals from their oxides. This helps extract metals like iron and manganese.
Q. Explain how the tendency to attain noble gas configuration governs the reactivity of metals and non‑metals.
Answer: Metals lose electrons to get stable configuration like noble gases. Non‑metals gain electrons to complete their octet. This tendency governs their reactivity.
Q. Why do ionic compounds have high melting and boiling points? Relate this to inter‑ionic forces.
Answer: Ionic compounds have strong forces between positive and negative ions. A lot of energy is needed to break these forces, so they have high melting and boiling points.
Q. How does the formation of NaCl illustrate the give‑and‑take nature of electron transfer?
Answer: Sodium gives one electron, chlorine takes one electron. This give‑and‑take forms Na⁺ and Cl⁻ ions, which combine to form NaCl.
Q. Explain how the position of a metal in the reactivity series decides its method of extraction.
Answer:
- Highly reactive metals are extracted by electrolysis.
- Medium reactive metals are reduced by carbon or displacement.
- Low reactive metals are extracted by heating alone.
Q. Why is carbon used as a reducing agent for metals of medium reactivity but not for highly reactive metals?
Answer: Carbon can remove oxygen from oxides of medium reactive metals. But highly reactive metals have stronger bonds with oxygen, so carbon cannot reduce them.
Q. How does the process of refining ensure purity of metals like copper and zinc?
Answer: In electrolytic refining, impure metal is made the anode and pure metal is deposited on the cathode. Impurities settle as anode mud. This gives pure metal.
Q. Explain how galvanisation protects iron from rusting.
Answer: Iron is coated with zinc. Zinc reacts first and prevents iron from rusting.
Q. Why is alloying considered a better method of improving metal properties than painting or greasing?
Answer: Alloying changes the internal structure of metals, making them stronger and resistant to rust. Painting or greasing only gives temporary protection.
Q. How does the structure of the Iron Pillar of Delhi demonstrate ancient Indian knowledge of metallurgy?
Answer: The Iron Pillar has not rusted for 1600 years. This shows that ancient Indians knew how to make iron resistant to corrosion by special methods of metallurgy.
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