Metals and Non-metals is a high-yield, reaction-heavy chapter in the current 2026-27 CBSE Class 10 Science syllabus. Below are complete, verified solutions to the end-of-chapter exercise.
NCERT Solutions for Class 10 Science Chapter 3: Metals and Non-metals
Q1. Which of the following pairs will give displacement reactions? (a) NaCl solution and copper metal (b) MgCl₂ solution and aluminium metal (c) FeSO₄ solution and silver metal (d) AgNO₃ solution and copper metal
Copper is more reactive than silver in the reactivity series, so it displaces silver from silver nitrate solution: Cu + 2AgNO₃ → Cu(NO₃)₂ + 2Ag.
Answer: (d).
Q2. Which of the following methods is suitable for preventing an iron frying pan from rusting? (a) Applying grease (b) Applying paint (c) Applying a coating of zinc (d) All of the above
Grease, paint and zinc coating all form a barrier stopping moisture and oxygen reaching the iron surface; zinc coating (galvanising) additionally protects iron sacrificially even if scratched.
Answer: (d).
Q3. An element reacts with oxygen to give a compound with a high melting point. This compound is also soluble in water. The element is likely to be: (a) calcium (b) carbon (c) silicon (d) iron
Metal oxides are generally high-melting ionic solids, and calcium oxide (CaO) is water-soluble, forming calcium hydroxide (a base). Non-metal oxides like those of carbon and silicon do not fit this description.
Answer: (a).
Q4. Food cans are coated with tin and not with zinc because: (a) zinc is costlier than tin (b) zinc is more reactive than tin (c) zinc is less reactive than tin (d) both (a) and (b)
Zinc is actually cheaper than tin, so (a) is false. The real reason is reactivity: zinc is more reactive than tin, so if the coating gets scratched, zinc would react with food acids faster and contaminate the food, whereas tin is comparatively unreactive and safer.
Answer: (b).
Q5. You are given a hammer, a battery, a bulb, wires and a switch. (a) How could you use them to distinguish between samples of metals and non-metals? (b) Assess the usefulness of these tests in distinguishing between metals and non-metals.
(a) Hammer test: strike each sample — metals flatten into a sheet (malleable) rather than break, while most non-metals shatter into pieces (brittle). Conductivity test: connect the sample in the circuit with the battery, bulb and switch; if the bulb lights, the sample conducts electricity.
(b) These are useful quick screening tests but not fully reliable: graphite (a non-metal) conducts electricity well; mercury is a metal that is liquid at room temperature, so the hammer test cannot apply to it; sodium and potassium are metals but are soft enough to cut with a knife. So the tests indicate a general trend, not an absolute rule.
Q6. What are amphoteric oxides? Give two examples of amphoteric oxides.
Amphoteric oxides are metal oxides that react with both acids and bases to produce salt and water, showing both acidic and basic character.
Examples: aluminium oxide (Al₂O₃) and zinc oxide (ZnO).
Q7. Name two metals which will displace hydrogen from dilute acids, and two metals which will not.
Will displace (more reactive than hydrogen): zinc and magnesium.
Will not displace (less reactive than hydrogen): copper and silver.
Q8. In the electrolytic refining of a metal M, what would you take as the anode, the cathode and the electrolyte?
Anode: a thick block of the impure metal M.
Cathode: a thin strip of pure metal M.
Electrolyte: a solution of a salt of the same metal M (e.g. for copper refining, acidified copper sulphate solution). On passing current, metal dissolves from the impure anode into solution and pure metal deposits on the cathode, while insoluble impurities settle below the anode as anode mud.
Q9. Pratyush took sulphur powder on a spatula and heated it. He collected the gas evolved by inverting a test tube over it. (a) What will be the action of the gas on moist blue litmus paper? (b) Write a balanced chemical equation for the reaction taking place.
(a) Sulphur burning in air produces sulphur dioxide, an acidic gas, so it will turn moist blue litmus paper red.
(b) S + O₂ → SO₂
Q10. State two ways to prevent the rusting of iron.
(i) Painting or applying grease/oil, which keeps moisture and air away from the iron surface.
(ii) Galvanisation — coating iron with a layer of zinc, which protects it sacrificially even if the coating is scratched.
Q11. What type of oxides are formed when non-metals combine with oxygen?
Non-metals generally form acidic oxides (occasionally neutral), which dissolve in water to form acids — e.g. SO₂ + H₂O → H₂SO₃ (sulphurous acid).
Q12. Give reasons: (a) Platinum, gold and silver are used to make jewellery. (b) Sodium, potassium and lithium are stored under oil. (c) Aluminium is a highly reactive metal, yet it is used to make utensils for cooking. (d) Carbonates and sulphides are usually converted into oxides during the extraction process.
(a) These metals sit very low in the reactivity series, so they resist corrosion and keep their lustre; they are also malleable and ductile, which suits ornament-making.
(b) Sodium, potassium and lithium react violently, even catching fire, on contact with air or water; storing them under kerosene oil isolates them from both.
(c) Aluminium reacts with atmospheric oxygen to form a thin, tough layer of aluminium oxide on its surface, which protects the metal underneath from further reaction — making it safe and durable for cookware despite its reactivity.
(d) Metal oxides are generally easier and more economical to reduce to the pure metal than carbonates or sulphides, so carbonate/sulphide ores are first converted to oxides (by calcination or roasting) before reduction.
Q13. You must have seen tarnished copper vessels being cleaned with lemon or tamarind juice. Explain why these sour substances are effective in cleaning the vessels.
Copper reacts slowly with moist air and CO₂ to form a dull green layer of basic copper carbonate on its surface. Lemon and tamarind juice contain weak acids (citric acid and tartaric acid respectively) that react with and dissolve this basic layer, restoring the shiny copper surface.
Q14. Differentiate between metal and non-metal on the basis of their chemical properties.
Metals: form basic oxides; lose electrons to form positive ions (cations); the more reactive ones displace hydrogen from dilute acids; generally do not react with bases (except amphoteric metals like aluminium and zinc).
Non-metals: form acidic or neutral oxides; gain electrons to form negative ions (anions); do not react with dilute acids to liberate hydrogen; some react with bases, e.g. chlorine with sodium hydroxide.
Q15. A man went door to door posing as a goldsmith and offered to melt customers’ old, dull gold jewellery and return it as shiny new-looking jewellery for a small fee. Explain, using chemistry, how a customer could verify whether the returned jewellery was still genuine gold.
Gold does not dissolve in ordinary acids, but it does dissolve in aqua regia (a freshly prepared 3:1 mixture of concentrated hydrochloric acid and concentrated nitric acid). A jeweller or customer can test a small scraping of the returned jewellery in aqua regia: if it dissolves the way pure gold should (without an unusual residue or resistance), and if the weight before and after the ‘polishing’ matches what was handed over, the gold is genuine and hasn’t been swapped for a cheaper alloy.
Q16. Give reasons why copper is used to make hot water tanks and not steel (an alloy of iron).
Copper does not react with water, even hot water, whereas iron (and steel) reacts with water/steam over time and corrodes. Copper is also a good conductor of heat, so it is a safer and more durable choice for hot water tanks despite being costlier than steel.
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