Where Mindful Learning Begins
Where Mindful Learning Begins
Class 10 Science NCERT Solutions Chapter 3 (CBSE 2026-27) — every in-text question, every embedded Activity question, and all 16 back-of-chapter Exercises on this one page, solved with the reasoning behind each answer.
Metals and Non-metals moves from the physical properties that make metals lustrous, malleable, ductile and sonorous, through their chemical reactions with oxygen, water, acids and salt solutions that build the reactivity series, to how metals and non-metals form ionic compounds by transferring electrons, how metals are extracted from their ores based on reactivity, and finally corrosion and how alloys change a metal's properties. These NCERT solutions work through every Activity-based question and the full 16-question Exercise set in detail, making this one of the most concept-dense chapters in the chemistry portion of the Class 10 Science syllabus.
Metals and Non-metals brings together the equation-writing skills from Chapter 1 and the acid-base ideas from Chapter 2 to build a complete picture of how metals behave. It moves from physical properties (lustre, malleability, ductility, conductivity, sonority) to chemical properties — how metals react with oxygen, water, dilute acids, and each other's salt solutions — which together build the reactivity series, one of the most useful tools in this chapter. From there it explains ionic bonding (why and how metals and non-metals transfer electrons to form compounds like NaCl and MgCl2), how metals are actually extracted from ores based on where they sit in the reactivity series, and finally corrosion and how alloying changes a metal's properties. Every question woven through the chapter is solved here, section by section, in the order the textbook presents it: the four "QUESTIONS" boxes after Sections 3.1 through 3.5, the questions embedded directly inside Activities and "Do You Know" boxes, and the full 16-question Exercise set at the end.
Lustre, malleability, ductility, sonority — and reactions with oxygen, water, acids and other metals' salt solutions that build the reactivity series.
How metals lose electrons and non-metals gain them to form stable ionic compounds like NaCl and MgCl2, and why these compounds behave the way they do.
How a metal's position in the reactivity series decides how it's extracted from its ore, why metals corrode, and how alloying changes a metal's properties.
(i) Mercury (Hg) is a liquid at room temperature.
(ii) Sodium (Na) or potassium (K) — soft alkali metals that can be easily cut with a knife.
(iii) Silver (Ag) is the best conductor of heat (copper is a close second).
(iv) Lead (Pb) or mercury (Hg) are comparatively poor conductors of heat.
Malleable: the property of a metal that allows it to be beaten (hammered or rolled) into thin sheets without breaking.
Ductile: the property of a metal that allows it to be drawn into thin wires.
Sodium is a highly reactive metal that reacts vigorously (and can even catch fire) with the oxygen and moisture present in air. Keeping it immersed in kerosene oil prevents it from coming into contact with air or moisture, protecting it from reacting and accidentally catching fire.
(i) Iron with steam:
(ii) Calcium and potassium with water:
From the table: A displaces Cu from CuSO4 but not Fe from FeSO4 (so Fe > A > Cu). B displaces Fe from FeSO4 but not Zn from ZnSO4 (so Zn > B > Fe). C displaces only Ag from AgNO3 (so Fe, Cu, Zn > C > Ag). D shows no reaction with anything (D is least reactive of all).
Combining these: Zn > B > Fe > A > Cu > C > Ag > D
(i) Among A, B, C, D, B is the most reactive metal.
(ii) Since B is more reactive than iron, and iron is more reactive than copper, B is also more reactive than copper. So if B is added to copper(II) sulphate solution, a displacement reaction would occur — the blue colour of the solution would fade, and reddish-brown copper would be deposited.
(iii) Decreasing order of reactivity of A, B, C, D: B > A > C > D
Hydrogen gas is produced.
Zinc is more reactive than iron, so it displaces iron from iron(II) sulphate solution. The pale green colour of the iron sulphate solution fades, and a greyish-black deposit of iron forms on the zinc.
(i) Electron-dot (Lewis) structures show the valence electrons as dots around the symbol: Sodium has 1 valence electron (Na with a single dot); oxygen has 6 valence electrons (O with six dots — two lone pairs and two single dots); magnesium has 2 valence electrons (Mg with two dots).
(ii) Formation of Na2O: two sodium atoms each donate their one valence electron to a single oxygen atom (which needs 2 electrons to complete its octet), forming two Na+ ions and one O2– ion.
Formation of MgO: one magnesium atom donates its 2 valence electrons to one oxygen atom.
(iii) Ions present: in Na2O — Na+ (sodium cation) and O2– (oxide anion); in MgO — Mg2+ (magnesium cation) and O2– (oxide anion).
Ionic compounds consist of oppositely charged ions held together by strong electrostatic forces of attraction throughout the crystal lattice. A considerable amount of energy is required to overcome these strong inter-ionic forces and separate the ions, which is why ionic compounds have high melting (and boiling) points.
(i) Mineral: elements or compounds that occur naturally in the earth's crust.
(ii) Ore: a mineral that contains a very high percentage of a particular metal, from which the metal can be profitably extracted.
(iii) Gangue: the impurities (such as soil and sand) mixed with an ore as it is mined from the earth.
Gold (Au) and Silver (Ag) (platinum is another common example) — these are least reactive metals and are often found uncombined in nature.
Reduction — heating the metal oxide with a suitable reducing agent (such as carbon), or, for highly reactive metals, electrolytic reduction (electrolysis of the molten oxide/chloride).
Using the reactivity order Mg > Zn > Cu:
| Metal oxide | + Zinc | + Magnesium | + Copper |
|---|---|---|---|
| Zinc oxide | No reaction | Displacement | No reaction |
| Magnesium oxide | No reaction | No reaction | No reaction |
| Copper oxide | Displacement | Displacement | No reaction |
Displacement reactions occur in: Zinc oxide + Magnesium (since Mg is more reactive than Zn); Copper oxide + Zinc, and Copper oxide + Magnesium (since both Zn and Mg are more reactive than Cu).
Metals low in the reactivity series — such as gold, silver, and platinum — do not corrode easily since they are highly unreactive.
An alloy is a homogeneous mixture of two or more metals, or a metal and a non-metal. It is prepared by first melting the primary metal, then dissolving the other element(s) into it in definite proportions, and cooling the mixture to room temperature. Alloys are made to improve a metal's properties, such as hardness or resistance to corrosion — for example, stainless steel, brass, and bronze.
Common metal wires seen in daily life include copper wires (household electrical wiring), aluminium wires (overhead power transmission lines), iron/steel wires (fencing, ropes), nichrome wires (heating elements in appliances like toasters and heaters), and silver/gold wires (used in fine jewellery and some electronics).
The metal wire inside is a good conductor of electricity, so touching a bare current-carrying wire would cause a dangerous electric shock. PVC and rubber-like materials are poor conductors of electricity (insulators), so coating the wire with them prevents the current from passing through to anyone who touches it, providing safety insulation.
Metals are sonorous — they produce a clear, ringing sound when struck against a hard surface. This property makes metals well suited for making bells, which need to produce a loud, resonant sound.
Metals such as aluminium and copper are commonly used for cooking vessels. This is because (as shown in Activity 3.5) metals are good conductors of heat and have high melting points, allowing them to transfer heat efficiently to food during cooking without melting or getting damaged.
Burning magnesium forms magnesium oxide, whose solution in water turns red litmus blue (and does not affect blue litmus) — it is basic.
Burning sulphur forms sulphur dioxide fumes, whose solution in water turns blue litmus red (and does not affect red litmus) — it is acidic.
Iron is more reactive than copper. The iron nail placed in copper sulphate solution shows a reaction — the blue colour fades and reddish-brown copper deposits on the nail — while the copper wire placed in iron sulphate solution shows no reaction. Since iron can displace copper from its salt solution but copper cannot displace iron, iron must be the more reactive metal.
Aluminium (Al) is getting oxidised — it gains oxygen to form Al2O3. Manganese dioxide (MnO2) is getting reduced — it loses oxygen to form Mn.
Even if the zinc coating is broken or scratched, the underlying iron is still protected because zinc is more reactive than iron. The zinc surrounding the exposed spot corrodes/oxidises preferentially in place of the iron (sacrificing itself), which protects the iron underneath from rusting until the zinc is used up — this is known as sacrificial protection.
Answer: (d) AgNO3 solution and copper metal
Copper is more reactive than silver, so it displaces silver from silver nitrate solution:
The other pairs show no reaction: copper cannot displace sodium (a), aluminium cannot displace magnesium (b, since Mg is more reactive than Al), and silver cannot displace iron (c).
Answer: (a) Applying grease
Since a frying pan is used for cooking, paint and zinc coating are not safe or suitable for a surface that comes into contact with food and heat — a thin film of edible oil/grease is the safe, practical method for a cooking vessel.
Answer: (a) calcium
Calcium forms calcium oxide (CaO), an ionic compound with a high melting point that reacts with/dissolves in water to form calcium hydroxide. Carbon and silicon form covalent oxides (CO2 is a gas; SiO2 is insoluble in water), and iron oxide is largely insoluble in water — so calcium fits best.
Answer: (c) zinc is more reactive than tin
Being more reactive, zinc would react with the acidic contents of the food, contaminating it and making it unsafe, whereas the less reactive tin does not react with food.
(a) Hammer test: strike each sample with the hammer. Metals are generally malleable and will flatten/change shape without breaking, whereas non-metals are typically brittle and shatter into pieces.
Conductivity test: connect the sample in a circuit made with the battery, bulb, wires and switch. If the bulb glows, the sample conducts electricity (likely a metal); if the bulb does not glow, the sample is likely a non-metal.
(b) These tests are useful general indicators but not fully conclusive, since there are exceptions — some metals (sodium, potassium) are too soft to behave typically under the hammer test, graphite (a non-metal) conducts electricity well, and iodine (a non-metal) is lustrous. Chemical properties give a more reliable classification.
Amphoteric oxides are metal oxides that react with both acids and bases to produce a salt and water, showing both acidic and basic behaviour. Examples: Aluminium oxide (Al2O3) and Zinc oxide (ZnO).
Will displace hydrogen (more reactive than hydrogen): Zinc (Zn) and Magnesium (Mg).
Will not displace hydrogen (less reactive than hydrogen): Copper (Cu) and Silver (Ag).
Anode: a thick block/rod of the impure metal M.
Cathode: a thin strip of pure metal M.
Electrolyte: a solution of a suitable salt of the metal M (e.g., for copper, acidified copper sulphate solution).
(a)(i) No effect on dry litmus paper — the gas (SO2) shows acidic character only in the presence of moisture.
(a)(ii) Moist blue litmus paper turns red, showing the gas is acidic.
(b)
(i) Painting the iron surface, to prevent contact with moisture and air.
(ii) Galvanisation — coating the iron with a thin layer of zinc. (Other valid answers: oiling/greasing, chrome plating, or alloying, e.g. making stainless steel.)
Non-metals generally form acidic oxides (or, in some cases, neutral oxides) when they combine with oxygen.
(a) These metals are very unreactive (low in the reactivity series), so they do not corrode or tarnish easily and retain their lustre for a long time — making them ideal for jewellery.
(b) These highly reactive alkali metals react vigorously with the oxygen and moisture in air (and can catch fire). Storing them under oil keeps them away from air/moisture, preventing this reaction.
(c) Although aluminium is reactive, it quickly forms a thin, tough layer of aluminium oxide on its surface in air. This protective layer prevents further reaction, and aluminium is also light, a good conductor of heat, and has a high melting point — making it suitable for cooking utensils.
(d) It is easier to reduce a metal oxide to the metal than to reduce it directly from a carbonate or sulphide ore. So carbonates are converted to oxides by calcination, and sulphides by roasting, before reducing the oxide to obtain the pure metal.
Tarnishing of copper is due to a layer of basic copper carbonate/oxide forming on its surface, which is basic in nature. Lemon and tamarind juice contain acids (citric acid, tartaric acid) that react with and dissolve this basic layer, restoring the shiny copper surface underneath.
| Property | Metals | Non-metals |
|---|---|---|
| Reaction with oxygen | Form basic oxides (Al2O3, ZnO are amphoteric) | Form acidic or neutral oxides |
| Reaction with water | Reactive metals form metal hydroxide/oxide and hydrogen gas | Generally do not react with water |
| Reaction with dilute acids | Metals above hydrogen displace hydrogen gas | Do not displace hydrogen from acids |
| Ion formation | Lose electrons to form positive ions (cations) | Gain electrons to form negative ions (anions) |
The solution used was most likely aqua regia — a freshly prepared mixture of concentrated hydrochloric acid and concentrated nitric acid in a 3:1 ratio, one of the few substances that can dissolve gold (even though neither acid can do so alone). Dipping the gold bangles in it would dissolve away a portion of the gold — making them lighter — while polishing the remaining surface to make it sparkle like new. This is how the man was able to cheat the lady, reducing the weight of her ornaments while making them look freshly cleaned.
Copper is less reactive than iron and does not react readily with water, even hot water, so it does not corrode. This makes it durable for use in hot water tanks. Steel (an alloy of iron), being more reactive, would react with hot water/steam over time, leading to rusting and corrosion of the tank — so copper is preferred over steel.
Next up is Chapter 4 — Carbon and Its Compounds. Or explore the full chapter list, browse the Class 10 Science hub, or book a free demo class for personalised coaching.
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