ScienceCBSE Class 10 · Chapter 3

Metals and Non-metals Class 10: Notes and Board Answers

Updated 14 October 2026 · Fact-checked

Metals and Non-metals compares the physical and chemical properties of metals and non-metals. It then builds the reactivity series, shows how ionic compounds form, and explains how metals are extracted, refined and protected from corrosion. The board asks for balanced equations, reasons, displacement predictions, extraction steps, electrolytic refining and activity-based questions on rusting.

What Metals and Non-metals is about

This chapter asks one big question: why do metals and non-metals behave so differently? You start with what you can see and touch (lustre, malleability, conduction). Then you test how metals react with oxygen, water, acids and salt solutions. These tests let you rank metals in the reactivity series. That one list explains almost everything that follows: which metal displaces which, why sodium gives up an electron so easily, how each metal is extracted, and why some metals corrode.

It links back to Chapter 1 (oxidation, reduction, displacement, corrosion) and Chapter 2 (acids, bases, basic and acidic oxides). The idea of a stable octet from Class IX explains ionic bonding here. The practical on putting Zn, Fe, Cu and Al into each other's sulphate solutions comes straight from this chapter.

Board questions come in a few clear shapes. You get MCQs and assertion-reason items on reactivity and oxides, and 'give reasons' questions such as why aluminium is used for cooking vessels. You will also see balanced equations for extraction and displacement, and electron-transfer diagrams for ionic compounds. Longer items include a labelled diagram of electrolytic refining, case-based passages on metallurgy or alloys, and activity questions on the three-test-tube rusting experiment.

Weightage: This chapter is part of Unit I, Chemical Substances: Nature and Behaviour, which carries 25 of the 80 theory marks together with Chemical Reactions and Equations, Acids, Bases and Salts and Carbon and its Compounds.Source: CBSE Science syllabus 2026-27, Unit I Chemical Substances: Nature and Behaviour

In real board papers: asked in 21 of the 21 board papers we hold (2023 to 2026), on average 6.5 marks per paper. See the questions

Key concepts

Physical properties of metals and non-metals

NCERT section 3.1 Physical Properties

Pure metals have a shiny surface (metallic lustre). They are generally hard. They can be beaten into sheets (malleable; gold and silver are the most malleable) and drawn into wires (ductile; gold is the most ductile). They conduct heat and electricity, have high melting points and ring when struck (sonorous). Silver and copper conduct heat best. Lead and mercury conduct heat comparatively poorly.

Non-metals are far fewer, for example carbon, sulphur, iodine, oxygen and hydrogen. They are solids or gases, except bromine, which is a liquid. They are neither malleable nor ductile and are bad conductors, except graphite.

Why can't you sort elements by these properties alone? Because there are too many exceptions:

mercury is a liquid metal
gallium and caesium melt on your palm
iodine is a lustrous non-metal
diamond (carbon) is the hardest natural substance and has a very high melting point
graphite conducts electricity
lithium, sodium and potassium are soft enough to cut with a knife

That is why chemical properties give a clearer classification.

Worked example

Give reasons (3 marks):
(a) School bells are made of metal.
(b) Electric wires at home are made of copper but covered with a coating of PVC.
(c) Elements cannot be classified as metals or non-metals on the basis of physical properties alone.

Try it first, then show the solutionSolution

(a) Metals are sonorous: they produce a ringing sound when struck on a hard surface, so a metal bell can be heard clearly. (1 mark)
(b) Copper is ductile and a very good conductor of electricity, so it makes good current-carrying wire. PVC does not conduct, so the coating stops current reaching anyone who touches the wire. (1 mark)
(c) There are many exceptions. For example, mercury is a liquid metal, sodium is so soft it can be cut with a knife, iodine is a lustrous non-metal and graphite is a non-metal that conducts electricity. (1 mark)

Answer: (a) Metals are sonorous. (b) Copper is ductile and conducts well; the PVC coating is a non-conductor that protects the user. (c) Exceptions such as mercury, sodium, iodine and graphite break the general pattern.

Reaction of metals and non-metals with oxygen; basic, acidic and amphoteric oxides

NCERT section 3.2.1 What happens when Metals are burnt in Air?

Almost every metal combines with oxygen to form a metal oxide, for example $2 C u + O_{2} \to 2 C u O$ (black copper(II) oxide) and $4 A l + 3 O_{2} \to 2 A l_{2} O_{3}$ .

Metal oxides are basic. Most are insoluble, but sodium oxide and potassium oxide dissolve in water to form alkalis: $N a_{2} O (s) + H_{2} O (l) \to 2 N a O H (a q)$ .

Some oxides, such as aluminium oxide and zinc oxide, react with both acids and bases to give salt and water. These are amphoteric oxides.

Non-metals form oxides that are acidic or neutral. In Activity 3.8, burning sulphur gives fumes whose solution turns blue litmus red. Burning magnesium gives an ash whose solution turns red litmus blue. That difference is a chemical way to tell the two groups apart.

Metals also differ in how fast they react with oxygen:

Sodium and potassium catch fire in open air, so they are kept under kerosene.
Magnesium, aluminium, zinc and lead get a thin oxide layer that protects them from further oxidation.
Iron filings burn in a flame, but a block of iron does not.
Copper only turns black on its surface.
Silver and gold do not react even at high temperatures.

Worked example

Element X burns in air with a dazzling white flame. Its ash dissolves in water, and the solution turns red litmus blue. Element Y is a yellow powder; when it burns, the fumes dissolved in water turn blue litmus red. (3 marks)
(a) Identify X and Y and state the nature of their oxides.
(b) Write a balanced equation for the burning of each element.

Try it first, then show the solutionSolution

X is magnesium. Its oxide is basic, because the solution turns red litmus blue. (½ mark)
Y is sulphur. Its oxide is acidic, because the solution turns blue litmus red. (½ mark)
Burning X: $2 M g + O_{2} \to 2 M g O$ (1 mark)
Burning Y: $S + O_{2} \to S O_{2}$ (1 mark)

Answer: X = magnesium, which forms the basic oxide MgO by $2 M g + O_{2} \to 2 M g O$ . Y = sulphur, which forms the acidic oxide SO2 by $S + O_{2} \to S O_{2}$ .

Reaction of metals with water and dilute acids

NCERT section 3.2.2 What happens when Metals react with Water?

With water, a metal gives a metal oxide and hydrogen. If that oxide is soluble, it goes on to form a hydroxide. How easily this happens is a direct measure of reactivity:

Potassium and sodium react violently with cold water. The reaction gives out so much heat that the hydrogen catches fire: $2 N a (s) + 2 H_{2} O (l) \to 2 N a O H (a q) + H_{2} (g)$ + heat.
Calcium reacts less violently, so the hydrogen does not ignite. Hydrogen bubbles stick to the metal and make it float.
Magnesium reacts only with hot water and also floats.
Aluminium, iron and zinc react only with steam, giving the oxide: $3 F e (s) + 4 H_{2} O (g) \to F e_{3} O_{4} (s) + 4 H_{2} (g)$ .
Lead, copper, silver and gold do not react with water at all.

With dilute hydrochloric acid, metals above hydrogen in the series give a salt and hydrogen. The rate of bubbling and the rise in temperature fall in the order Mg > Al > Zn > Fe. Copper shows no bubbles at all.

Nitric acid is different. It is a strong oxidising agent, so it turns the hydrogen into water and itself becomes nitrogen oxides. The exceptions are magnesium and manganese, which give hydrogen with very dilute nitric acid.

Worked example

Three metals P, Q and R are sodium, magnesium and iron, in some order. P reacts violently with cold water and the gas evolved catches fire. Q does not react with cold water, but reacts with hot water and starts floating. R reacts only when steam is passed over it. (3 marks)
(a) Identify P, Q and R.
(b) Write the balanced equation for the reaction of R with steam.
(c) Why does Q float?

Try it first, then show the solutionSolution

P = sodium, Q = magnesium, R = iron. (1 mark)
$3 F e (s) + 4 H_{2} O (g) \to F e_{3} O_{4} (s) + 4 H_{2} (g)$ (1 mark)
Bubbles of hydrogen gas formed in the reaction stick to the surface of the magnesium and make it float. (1 mark)

Answer: P is sodium, Q is magnesium and R is iron. Iron with steam: $3 F e (s) + 4 H_{2} O (g) \to F e_{3} O_{4} (s) + 4 H_{2} (g)$ . Magnesium floats because hydrogen bubbles stick to its surface.

Displacement reactions and the reactivity series

NCERT section 3.2.5 The Reactivity Series

Oxygen, water and acids do not react with every metal, so they cannot rank all metals. Displacement gives cleaner evidence. If metal A pushes metal B out of B's salt solution, A is more reactive than B. If nothing happens, B is more reactive.

In Activity 3.12, an iron nail in copper sulphate solution gets coated with copper:

$F e (s) + C u S O_{4} (a q) \to F e S O_{4} (a q) + C u (s)$

A copper wire in iron sulphate solution shows no change. So iron is more reactive than copper.

Putting many such results together gives the reactivity series: K, Na, Ca, Mg, Al, Zn, Fe, Pb, [H], Cu, Hg, Ag, Au, from most to least reactive.

Hydrogen sits in the list as a marker. Metals above it can displace hydrogen from dilute acids. Metals below it, such as copper and silver, cannot.

The series lets you predict reactions:

zinc will displace iron from iron(II) sulphate
silver will not displace anything from copper sulphate

It also explains extraction methods and corrosion later in the chapter. Learn it in order.

Worked example

In a practical, a student puts clean strips of Al, Zn, Fe and Cu into solutions of $A l_{2} (S O_{4})_{3}$ , $Z n S O_{4}$ , $F e S O_{4}$ and $C u S O_{4}$ . She records:

Al shows a deposit in the ZnSO4, FeSO4 and CuSO4 solutions.
Zn shows a deposit only in the FeSO4 and CuSO4 solutions.
Fe shows a deposit only in the CuSO4 solution.
Cu shows no change in any solution.

(a) Arrange the four metals in decreasing order of reactivity.
(b) Write a balanced equation for the reaction of zinc with iron(II) sulphate.
(c) Which metal sulphate solution could safely be stored in a container made of any of these four metals? Justify. (3 marks)

Try it first, then show the solutionSolution

Al displaces three metals, Zn displaces two, Fe displaces one and Cu displaces none. So the order is Al > Zn > Fe > Cu. (1 mark)
$Z n (s) + F e S O_{4} (a q) \to Z n S O_{4} (a q) + F e (s)$ (1 mark)
Aluminium sulphate solution. Aluminium is the most reactive of the four, so none of the other metals can displace it, and the container will not react. (1 mark)

Answer: (a) Al > Zn > Fe > Cu. (b) $Z n (s) + F e S O_{4} (a q) \to Z n S O_{4} (a q) + F e (s)$ . (c) Aluminium sulphate solution, because no less reactive metal can displace aluminium.

Formation of ionic compounds by transfer of electrons

NCERT section 3.3 How do Metals and Non-metals React?

Noble gases have a completely filled outer shell and show little chemical activity. Other atoms react so that they reach a filled outer shell too.

Sodium (2,8,1) can lose one electron. Its L shell then becomes the outer shell with a stable octet. It still has 11 protons but only 10 electrons, so it becomes $N a^{+}$ .

Chlorine (2,8,7) needs one electron. After gaining it, it has 17 protons and 18 electrons, so it becomes $C l^{-}$ .

The electron sodium loses is the one chlorine gains. The oppositely charged ions then attract strongly through electrostatic forces and form sodium chloride. NaCl is not made of molecules. It is a large aggregate of $N a^{+}$ and $C l^{-}$ ions.

Magnesium (2,8,2) loses two electrons to become $M g^{2 +}$ . It needs two chlorine atoms, giving $M g C l_{2}$ . With oxygen (2,6), which gains two electrons to become $O^{2 -}$ , it forms MgO.

Compounds made this way, by electron transfer from a metal to a non-metal, are called ionic or electrovalent compounds.

In short, metals form positive ions by losing electrons and non-metals form negative ions by gaining them.

Worked example

(a) Write the electronic configurations of magnesium (atomic number 12) and oxygen (atomic number 8).
(b) Show the formation of magnesium oxide by the transfer of electrons, using electron-dot structures.
(c) Name the ions present. (3 marks)

Try it first, then show the solutionSolution

Mg: 2,8,2. O: 2,6. (½ mark)
Electron-dot structures: write Mg with 2 dots (its 2 valence electrons) and O with 6 dots (its 6 valence electrons). (½ mark)
Draw curved arrows from the 2 dots on Mg to O. Show the products as $[M g]^{2 +}$ and $[O]^{2 -}$ , with O inside brackets showing 8 dots. Write $M g \to M g^{2 +} + 2 e^{-}$ and $O + 2 e^{-} \to O^{2 -}$ . (1 mark)
Ions present: magnesium cation $M g^{2 +}$ and oxide anion $O^{2 -}$ . They are held together by strong electrostatic attraction. (1 mark)

Answer: Mg (2,8,2) transfers 2 electrons to O (2,6), forming $M g^{2 +}$ (2,8) and $O^{2 -}$ (2,8). These ions are held by electrostatic attraction as $M g^{2 +} O^{2 -}$ , that is, MgO.

Properties of ionic compounds

NCERT section 3.3.1 Properties of Ionic Compounds

Every property of an ionic compound comes from one fact: strong attraction between oppositely charged ions held in a rigid arrangement.

Physical nature: they are solid and somewhat hard, because the attraction is strong. They are generally brittle and break into pieces when pressure is applied.
Melting and boiling points: high, because a lot of energy is needed to overcome the inter-ionic attraction. For example, NaCl melts at 1074 K and CaO at 2850 K.
Solubility: generally soluble in water, but insoluble in kerosene and petrol.
Conduction of electricity: a current needs moving charged particles. In the solid, the ions are locked in place by the rigid structure, so the solid does not conduct. In water, the ions are free and move to the opposite electrodes, so the solution conducts. When the solid is melted, heat overcomes the attraction, the ions move freely, and the molten compound conducts.

This molten-state conduction is exactly what makes electrolytic extraction of sodium possible later in the chapter.

Worked example

Give reasons (3 marks):
(a) Ionic compounds have high melting points.
(b) Solid sodium chloride does not conduct electricity.
(c) Molten sodium chloride conducts electricity.

Try it first, then show the solutionSolution

(a) The oppositely charged ions are held by strong electrostatic forces, and a considerable amount of energy is needed to break this attraction. (1 mark)
(b) In the solid, the ions are held in a rigid structure and cannot move, so no charge flows. (1 mark)
(c) On melting, heat overcomes the attraction between the ions. The ions then move freely towards the oppositely charged electrodes and carry the current. (1 mark)

Answer: (a) Strong inter-ionic attraction needs a lot of energy to break. (b) The ions cannot move in the rigid solid. (c) In the melt, the ions are free to move and carry charge.

Occurrence of metals and extraction according to reactivity

NCERT section 3.4.4 Extracting Metals in the Middle of the Activity Series

Metals come mainly from the earth's crust; seawater also holds salts such as sodium chloride. A naturally occurring element or compound is a mineral. A mineral from which a metal can be extracted profitably is an ore.

Ores come mixed with soil and sand, called gangue. Gangue is removed first, using differences in physical or chemical properties (enrichment).

The method of extraction then depends on reactivity:

Low reactivity (for example mercury, and copper from $C u_{2} S$ ): heating in air alone is enough. $2 H g S + 3 O_{2} heat 2 H g O + 2 S O_{2}$ , then $2 H g O heat 2 H g + O_{2}$ .

Middle (Zn, Fe, Pb): these occur as sulphides or carbonates, and an oxide is easier to reduce. So you first convert the ore to an oxide:

sulphides by roasting (strong heating in excess air)
carbonates by calcination (strong heating in limited air)

Then reduce the oxide with carbon: $Z n O + C \to Z n + C O$ . A more reactive metal can also be the reducing agent, as in the thermit reaction.

Top (K, Na, Ca, Mg, Al): these metals hold oxygen more strongly than carbon does, so carbon cannot reduce their oxides. They are obtained by electrolysis of the molten chloride (or of aluminium oxide). The metal forms at the cathode.

Worked example

Zinc occurs as two ores. Ore A gives off carbon dioxide when heated strongly in limited air. Ore B gives off sulphur dioxide when heated strongly in excess air. (5 marks)
(a) Name ore A and ore B by their formulae and name the process applied to each.
(b) Write balanced equations for both processes.
(c) Write the equation for obtaining zinc from the product.
(d) Why are these ores converted to the oxide first?
(e) Why can sodium not be extracted in the same way?

Try it first, then show the solutionSolution

Ore A is $Z n C O_{3}$ , which undergoes calcination. Ore B is $Z n S$ , which undergoes roasting. (1 mark)
Calcination: $Z n C O_{3} (s) heat Z n O (s) + C O_{2} (g)$ (½ mark)
Roasting: $2 Z n S (s) + 3 O_{2} (g) heat 2 Z n O (s) + 2 S O_{2} (g)$ (1 mark)
Reduction with carbon: $Z n O (s) + C (s) \to Z n (s) + C O (g)$ . Zinc oxide is reduced and carbon is oxidised. (1 mark)
It is easier to obtain a metal from its oxide than from its sulphide or carbonate. (½ mark)
Sodium is near the top of the reactivity series and has more affinity for oxygen than carbon has, so carbon cannot reduce its oxide. Sodium is obtained by electrolysis of molten NaCl, with $N a^{+} + e^{-} \to N a$ at the cathode. (1 mark)

Answer: A = ZnCO3 (calcination) and B = ZnS (roasting); both give ZnO, which carbon reduces to zinc. Sodium binds oxygen more strongly than carbon does, so it must be obtained by electrolytic reduction of its molten chloride.

Refining of metals: electrolytic refining

NCERT section 3.4.6 Refining of Metals

Metals produced by reduction still contain impurities. The most widely used method of purifying them is electrolytic refining. It is used for copper, zinc, tin, nickel, silver, gold and others.

The set-up for copper:

anode: a thick block of impure copper
cathode: a thin strip of pure copper
electrolyte: acidified copper sulphate solution

When current passes, copper from the anode dissolves into the electrolyte as ions. An equal amount of pure copper from the electrolyte is deposited on the cathode. The anode therefore slowly gets thinner and the cathode gets thicker.

Impurities separate in two ways. Soluble impurities go into the solution. Insoluble impurities settle below the anode as anode mud.

Why this arrangement? Metal ions are positive, so they are attracted to the negative cathode. That is why the pure strip must be the cathode.

For any metal M, the rule is the same: impure M is the anode, pure M is the cathode, and a soluble salt of M is the electrolyte.

Worked example

Draw a labelled diagram of the electrolytic refining of copper. State what happens at each electrode when current is passed, and where the impurities go. (3 marks)

Try it first, then show the solutionSolution

Draw and label: a tank (electrolytic cell) filled with electrolyte labelled 'acidified copper sulphate solution'. (½ mark)
Draw a thick block on one side, labelled 'anode (impure copper)', and connect it to the positive (+) terminal of a battery. (½ mark)
Draw a thin strip on the other side, labelled 'cathode (pure copper)', and connect it to the negative (−) terminal. (½ mark)
Draw sediment at the bottom below the anode, labelled 'anode mud'. Common slip: swapping the anode and cathode. (½ mark)
At the anode, impure copper dissolves into the solution. At the cathode, an equivalent amount of pure copper is deposited. (½ mark)
Soluble impurities stay in the solution; insoluble impurities collect below the anode as anode mud. (½ mark)

Answer: Impure copper is the anode (+), a pure copper strip is the cathode (−) and acidified copper sulphate is the electrolyte. Copper dissolves from the anode and pure copper deposits on the cathode. Soluble impurities go into the solution and insoluble ones form anode mud.

Corrosion, its prevention and alloys

NCERT section 3.5.1 Prevention of Corrosion

Corrosion is the slow attack on a metal surface by moist air:

silver turns black (silver sulphide, from sulphur in the air)
copper gains a green coat (basic copper carbonate, from moist carbon dioxide)
iron gets brown, flaky rust

Activity 3.14 shows that iron needs both air and water to rust:

Tube A (water and air): the nails rust.
Tube B (boiled distilled water with an oil layer, so no dissolved air): no rust.
Tube C (anhydrous calcium chloride drying the air): no rust.

Prevention works by keeping air and water away, or by changing the metal: painting, oiling, greasing, galvanising, chrome plating, anodising or alloying.

Galvanising coats iron with zinc. The iron stays protected even if the coat cracks, because zinc is more reactive than iron and reacts in its place.

An alloy is a uniform blend made by melting a main metal and then dissolving other elements in it in set proportions. The added elements can be metals or non-metals. If one metal is mercury, the alloy is an amalgam. Some examples:

Pure iron is soft. With about 0.05% carbon it becomes hard and strong.
Iron with nickel and chromium gives stainless steel, which does not rust.
Brass (Cu, Zn) and bronze (Cu, Sn) are poorer conductors than copper.
Solder (Pb, Sn) has a low melting point, so it is used to join electrical wires.

Worked example

In an experiment, clean iron nails are placed in three test tubes. Tube A has ordinary water and is corked. Tube B has boiled distilled water with a layer of oil on top and is corked. Tube C has anhydrous calcium chloride and is corked. (3 marks)
(a) In which tube do the nails rust after a few days?
(b) Why is the water in B boiled, and why is oil added?
(c) What is the role of anhydrous calcium chloride in C?
(d) What do you conclude?

Try it first, then show the solutionSolution

(a) Only in tube A, where both air and water are present. (½ mark)
(b) Boiling removes the dissolved air from the water; the oil layer stops air from dissolving in it again. So the nails in B meet only water. (1 mark)
(c) Anhydrous calcium chloride absorbs moisture, so the air in C is dry. (½ mark)
(d) Iron rusts only when both air (oxygen) and water (moisture) are present together. (1 mark)

Answer: Rusting occurs only in tube A. Boiling and the oil layer keep air out of B, and calcium chloride keeps C dry, so iron needs both air and moisture to rust.

Science in real life: Metals and Non-metals

Each concept, met in an everyday situation. Read the situation, try the problem, then check the solution. The one-line hook is what to remember.

Physical properties of metals and non-metals

Imagine an electrician is replacing the wiring in your home. The wires are made of copper and each one is wrapped in a PVC coating. Your younger sibling asks why the metal inside is copper and not graphite pencil lead, since both conduct electricity.

Using physical properties, explain (a) why copper is preferred over graphite for house wiring, and (b) why the coating is needed. (3 marks)

Try it first, then show the solutionSolution

Copper is ductile, so it can be drawn into long, thin, flexible wires. (1 mark)
Graphite is a non-metal: it conducts electricity but is neither malleable nor ductile, so it cannot be drawn into wire. (1 mark)
PVC does not conduct electricity, so the coating stops current reaching a person who touches the wire. (1 mark)

Answer: Copper is a ductile, good conductor that can be made into wire, but graphite is not ductile. The non-conducting PVC coating protects users from shock.

Memory hook: Copper carries the current; PVC keeps it in.

Reaction of metals and non-metals with oxygen; basic, acidic and amphoteric oxides

Suppose your family has used the same aluminium pressure cooker for years. A cousin argues that aluminium is near the top of the reactivity series, so the cooker should have reacted with air and fallen apart long ago.

Explain why aluminium is used for cooking vessels even though it is a highly reactive metal, and state two other properties that make it suitable. (3 marks)

Try it first, then show the solutionSolution

At ordinary temperature, aluminium is covered with a thin layer of aluminium oxide. (1 mark)
This oxide layer protects the metal from further oxidation, so it does not keep corroding. (1 mark)
Aluminium is also a good conductor of heat and has a high melting point, so it heats food well without melting. (1 mark)

Answer: A protective oxide layer stops further reaction, and aluminium conducts heat well and has a high melting point.

Memory hook: Aluminium wears its own oxide armour.

Displacement reactions and the reactivity series

Imagine the school gardener has some copper sulphate solution for the garden. He plans to store it overnight in an old iron bucket, and another bucket made of copper is also available.

Should he use the iron bucket? Predict what would happen, write the equation, and suggest the better container. (3 marks)

Try it first, then show the solutionSolution

Iron is above copper in the reactivity series. (½ mark)
So iron would displace copper from the solution: $F e (s) + C u S O_{4} (a q) \to F e S O_{4} (a q) + C u (s)$ . (1 mark)
The bucket would get a reddish-brown copper coating and its iron would slowly be eaten away, and the solution would no longer be pure copper sulphate. (1 mark)
Use the copper bucket: copper cannot displace itself, so no reaction occurs. (½ mark)

Answer: No. The iron bucket would react by $F e + C u S O_{4} \to F e S O_{4} + C u$ ; he should store the solution in the copper bucket.

Memory hook: Never keep a salt in a bucket of a metal that sits above it.

Properties of ionic compounds

Suppose you set up the circuit from Activity 3.13 at home: a cell, a torch bulb and two wires dipped in a cup. You try a heap of dry table salt first, then the same salt stirred into water.

Predict what the bulb does in each case and explain the difference using the structure of sodium chloride. (3 marks)

Try it first, then show the solutionSolution

Dry salt: the bulb does not glow. (½ mark)
In the solid, the $N a^{+}$ and $C l^{-}$ ions are held in a rigid structure and cannot move. (1 mark)
Salt solution: the bulb glows. (½ mark)
In water, the ions are free to move towards the oppositely charged wires and carry the current. (1 mark)

Answer: The bulb does not glow with dry salt, because its ions are fixed, but it glows with salt solution, because the ions are free to move.

Memory hook: Salt conducts only when its ions can swim.

Occurrence of metals and extraction according to reactivity

Imagine you are at a railway crossing and see workers joining two rail ends. They pack a powder mixture into a mould around the gap, light it, and glowing molten iron flows into the joint.

Name the reaction, write its balanced equation, and explain why the iron comes out molten and why aluminium can reduce iron(III) oxide. (3 marks)

Try it first, then show the solutionSolution

This is the thermit reaction: $F e_{2} O_{3} (s) + 2 A l (s) \to 2 F e (l) + A l_{2} O_{3} (s)$ + heat. (1 mark)
The reaction is highly exothermic; so much heat is released that the iron is produced in the molten state and fills the gap. (1 mark)
Aluminium is more reactive than iron, so it takes the oxygen from iron(III) oxide and displaces iron. (1 mark)

Answer: The thermit reaction, $F e_{2} O_{3} + 2 A l \to 2 F e + A l_{2} O_{3}$ + heat. It is very exothermic, so the iron melts, and aluminium is more reactive than iron.

Memory hook: Thermit: aluminium steals oxygen and pays in heat.

Corrosion, its prevention and alloys

Suppose a family leaves one bicycle out in the rain all monsoon while a second one stays in a dry room. The gate outside their house is galvanised, and the grandmother's silver anklet has turned black.

(a) Which bicycle rusts and why? (b) The gate has a scratch, yet it does not rust there. Explain. (c) What is the black layer on the anklet? (3 marks)

Try it first, then show the solutionSolution

The outdoor bicycle rusts, because its iron is exposed to both air and water; the indoor one meets dry air only. (1 mark)
Galvanising coats iron with zinc. Zinc is more reactive than iron, so it reacts first and protects the iron even where the coat is broken. (1 mark)
Silver reacts with sulphur in the air to form a black coating of silver sulphide. (1 mark)

Answer: (a) The outdoor bicycle, because it has both air and moisture. (b) The more reactive zinc protects the iron even at the scratch. (c) Silver sulphide.

Memory hook: Rust needs air plus water; zinc takes the hit for iron.

Topics in this chapter

Physical Properties of Metals and Non-metalsComing soon
Chemical Properties of Metals
Reactivity Series of MetalsComing soon
Ionic Compounds: Formation and Properties
Metallurgy: Extraction of Metals from Ores
Corrosion and Its PreventionComing soon
Periodic Classification of Elements

Metals and Non-metals: formulas and key facts

Metal + oxygen: $2 C u + O_{2} \to 2 C u O; 4 A l + 3 O_{2} \to 2 A l_{2} O_{3}$; Metal oxides are basic. Use these when a question asks what forms on heating a metal in air; CuO is black.
Soluble metal oxide forms an alkali: $N a_{2} O (s) + H_{2} O (l) \to 2 N a O H (a q); K_{2} O (s) + H_{2} O (l) \to 2 K O H (a q)$; Only a few metal oxides dissolve in water; these give alkalis.
Amphoteric oxide (aluminium oxide): $A l_{2} O_{3} + 6 H C l \to 2 A l C l_{3} + 3 H_{2} O; A l_{2} O_{3} + 2 N a O H \to 2 N a A l O_{2} + H_{2} O$; Amphoteric oxides react with both acids and bases to give salt and water. NaAlO2 is sodium aluminate. ZnO is also amphoteric.
Non-metal oxide: $S + O_{2} \to S O_{2}$; Non-metal oxides are acidic or neutral. The SO2 solution turns blue litmus red.
Metals with water: $2 N a (s) + 2 H_{2} O (l) \to 2 N a O H (a q) + H_{2} (g); C a (s) + 2 H_{2} O (l) \to C a (O H)_{2} (a q) + H_{2} (g)$; Potassium follows the same pattern as sodium. Na and K react violently and the hydrogen catches fire; Ca floats. Mg needs hot water.
Metals with steam: $3 F e (s) + 4 H_{2} O (g) \to F e_{3} O_{4} (s) + 4 H_{2} (g); 2 A l (s) + 3 H_{2} O (g) \to A l_{2} O_{3} (s) + 3 H_{2} (g)$; Al, Fe and Zn react only with steam and give the oxide, not the hydroxide. Pb, Cu, Ag and Au do not react with water.
Metal + dilute acid: $M g + 2 H C l \to M g C l_{2} + H_{2}; F e + H_{2} S O_{4} \to F e S O_{4} + H_{2}$; Only metals above hydrogen do this. Rate with HCl: Mg > Al > Zn > Fe; copper does not react. Nitric acid generally gives no H2 because it is a strong oxidising agent; Mg and Mn give H2 only with very dilute HNO3.
Displacement rule: $F e (s) + C u S O_{4} (a q) \to F e S O_{4} (a q) + C u (s)$; A more reactive metal displaces a less reactive metal from its salt solution. If no reaction happens, the metal added is less reactive.
Reactivity series: $K > N a > C a > M g > A l > Z n > F e > P b > [H] > C u > H g > A g > A u$; Use this for every displacement, acid-reaction and extraction prediction.
Ion formation: $N a \to N a^{+} + e^{-}; C l + e^{-} \to C l^{-}; M g \to M g^{2 +} + 2 e^{-}$; Metals lose electrons to form cations; non-metals gain electrons to form anions. Configurations: Na 2,8,1 becomes 2,8; Cl 2,8,7 becomes 2,8,8.
Extraction of low-reactivity metals by heating alone: $2 H g S + 3 O_{2} heat 2 H g O + 2 S O_{2}; 2 H g O heat 2 H g + O_{2}$; Copper follows the same idea: $2 C u_{2} S + 3 O_{2} heat 2 C u_{2} O + 2 S O_{2}$ , then $2 C u_{2} O + C u_{2} S heat 6 C u + S O_{2}$ .
Roasting and calcination: $2 Z n S + 3 O_{2} heat 2 Z n O + 2 S O_{2}; Z n C O_{3} heat Z n O + C O_{2}$; Roasting: sulphide ore, strong heating in excess air. Calcination: carbonate ore, strong heating in limited air.
Reduction of an oxide: $Z n O + C \to Z n + C O$; Used for middle-of-series metals. Carbon (coke) is the reducing agent; it is oxidised while the metal oxide is reduced.
Reduction by a reactive metal (thermit): $F e_{2} O_{3} (s) + 2 A l (s) \to 2 F e (l) + A l_{2} O_{3} (s) + heat$; Highly exothermic, so the iron comes out molten; used to join railway tracks and cracked machine parts. Also $3 M n O_{2} + 4 A l \to 3 M n + 2 A l_{2} O_{3}$ + heat.
Electrolysis of molten NaCl: $Cathode: N a^{+} + e^{-} \to N a; Anode: 2 C l^{-} \to C l_{2} + 2 e^{-}$; For K, Na, Ca, Mg and Al, which carbon cannot reduce. The metal always forms at the cathode (negative electrode).
Rusting and alloy facts: Rust needs both air and water; an alloy is a uniform blend of a metal with other elements; Iron kept with only water (no dissolved air) or only dry air does not rust. To make an alloy, the main metal is melted and the other elements are dissolved in it in fixed amounts. Examples: steel (Fe + about 0.05% C), stainless steel (Fe, Ni, Cr), brass (Cu, Zn), bronze (Cu, Sn), solder (Pb, Sn); an alloy containing mercury is called an amalgam.

Metals and Non-metals: diagrams to practise

Practise each one on paper: draw it from the checklist, then tick off every label.

Electrolytic refining of copper

Draw-and-label questions (2-3 marks), often with 'state what happens when current is passed' or a case-based passage on refining.

Draw

A rectangular tank (electrolytic cell) filled about three-quarters with liquid.
A thick plate on one side dipping into the liquid: the impure copper.
A thin strip on the other side dipping into the liquid: the pure copper.
A battery outside the tank, with wires joining its positive terminal to the thick impure plate and its negative terminal to the thin pure strip; add a switch or key in the circuit.
A small heap of sludge at the bottom of the tank, directly below the impure copper plate.
Optional: small arrows in the liquid from the anode towards the cathode to show copper moving across.

Label

Anode (impure copper), connected to +
Cathode (thin strip of pure copper), connected to −
Electrolyte: acidified copper sulphate solution
Anode mud (insoluble impurities)
Battery / power supply
Tank (electrolytic cell)

Watch out: The slip to avoid is swapping the electrodes. Impure copper is always the anode (+) because it must dissolve; pure copper is the cathode (−) because copper is deposited on it. Draw the anode mud under the anode, not under the cathode, and write 'acidified' before copper sulphate.

Activity 3.14: conditions needed for rusting of iron

Activity-based questions asking you to draw or describe the three-test-tube set-up and explain the result.

Draw

Three corked test tubes side by side, marked A, B and C, each with clean iron nails inside.
Tube A: ordinary water partly covering the nails, with air above it.
Tube B: boiled distilled water covering the nails, with a thin layer of oil floating on top of the water.
Tube C: no water; a layer of anhydrous calcium chloride at the bottom with nails resting in dry air.
Show rust (brown patches) only on the nails in tube A.

Label

A: air and water present (nails rust)
B: boiled distilled water, layer of oil (no dissolved air)
C: anhydrous calcium chloride, dry air
Iron nails
Cork

Watch out: Do not forget the oil layer in B or the cork on all three tubes. Say why: boiling removes dissolved air, oil stops air dissolving again, and calcium chloride absorbs moisture. Conclusion must mention both air and water.

Formation of an ionic compound by electron transfer (NaCl or MgCl2)

Short answers asking you to 'show the formation' of NaCl, MgCl2, Na2O, MgO or CaCl2 using electron-dot structures.

Draw

Write the symbol of the metal atom with its valence electrons as dots or crosses around it (Na with one, Mg with two).
Write the symbol of each non-metal atom with its valence electrons (Cl with seven, O with six), using a different mark from the metal.
Draw curved arrows from each metal electron to the non-metal atom that receives it.
After an arrow, write the ions in square brackets with their charges, showing the full octet on the anion.
Write the configurations under each particle: Na 2, 8, 1 to Na+ 2, 8; Cl 2, 8, 7 to Cl− 2, 8, 8.

Label

Metal atom and its configuration
Non-metal atom and its configuration
Arrow showing electron transfer
Cation with charge (Na+ or Mg2+)
Anion with charge (Cl−)
Name of the compound formed

Watch out: Use two chlorine atoms for MgCl2, since magnesium gives away two electrons. Do not draw shared pairs of dots between the atoms: that is covalent bonding, not ionic. Always write the charges on the ions.

Activity 3.5: metals conduct heat

Activity-based questions on conduction of heat and high melting points of metals.

Draw

A stand with a clamp holding an aluminium or copper wire horizontally.
A pin stuck with wax to the free end of the wire.
A spirit lamp, candle or burner below the wire near the clamped end.
Show the pin falling off after some time.

Label

Stand and clamp
Aluminium or copper wire
Wax
Pin
Spirit lamp / burner

Watch out: Heat is applied near the clamp, not at the pin end. State both conclusions: the wax melts so metals conduct heat, and the wire itself does not melt so metals have high melting points.

Activity 3.6 / 3.13: testing conduction of electricity

Questions on distinguishing metals from non-metals, or on whether a salt conducts when solid, dissolved or molten.

Draw

A cell or battery, a switch and a torch bulb joined in series by wires.
For a solid sample: leave a gap between two terminals A and B and place the sample across the gap.
For a solution: let two electrodes (ends of the wires) dip into a beaker of the salt solution.

Label

Battery / cell
Switch
Bulb
Terminals A and B (or electrodes)
Sample under test / salt solution

Watch out: The circuit must be complete through the sample only; do not let the electrodes touch each other. Glowing bulb means the sample conducts. Remember graphite is the non-metal that conducts.

How the board asks Metals and Non-metals

The question patterns to expect, and the method that works for each.

Question type	How it is asked	Method
Displacement and reactivity predictions (MCQ or short answer)	You are given pairs such as a metal and a salt solution and asked which react, or a table of results for unknown metals A, B, C and D, and asked to rank them or predict an observation.	Write the reactivity series in the margin first. For each pair, check whether the metal is above the metal in the salt. For unknowns, count how many solutions each metal displaces from: more displacements means more reactive. Write the equation only for pairs that react.
Assertion-reason on properties, oxides or extraction	Two statements, such as 'Carbon cannot reduce sodium oxide' with a reason about affinity for oxygen, or a true reason that is unrelated to the assertion.	Judge A and R separately as true or false. Then ask whether R actually explains A. A true but unrelated R gives option (b), not (a).
Give reasons	Three to five parts, for example: sodium is kept under kerosene; aluminium is used for cooking vessels; ionic compounds conduct when molten; carbonate ores are changed to oxides; a galvanised article is protected even when scratched.	Give one cause-and-effect sentence for each part, naming the property involved (reactivity, protective oxide layer, mobile ions, ease of reducing oxides, zinc more reactive than iron). Add an equation if it helps.
Balanced equations and electron transfer	Write equations for iron with steam, or calcium and potassium with water; show the formation of Na2O, MgO or MgCl2 by electron transfer and name the ions.	Count every atom on both sides and add state symbols when asked. For electron transfer, give the configurations, use dots for valence electrons, draw arrows from the metal to the non-metal, and show the charges on the products in brackets.
Case-based passage on metallurgy or alloys	A passage on calcination, roasting, reduction, electrolysis or alloy properties, followed by sub-questions on naming a process, writing an equation or explaining why an alloy is used.	Underline the reactivity clue in each part (top, middle or bottom of the series), then choose the method: electrolysis, oxide formation followed by carbon reduction, or heating alone. For alloys, remember they have lower conductivity and melting point than the pure metal.
Labelled diagram: electrolytic refining	Draw and label the refining of copper (or a metal M) and state what happens when current is passed.	Label the impure anode (+), the pure cathode (−), the electrolyte (acidified copper sulphate) and the anode mud. State that the metal dissolves from the anode, deposits on the cathode, and where soluble and insoluble impurities go.
Activity and practical-based questions	The three-test-tube rusting set-up, Activity 3.8 litmus tests on oxides, heat conduction along a wire with pins fixed by wax, or the practical with Zn, Fe, Cu and Al in sulphate solutions.	Answer in four parts: what was done, what was seen, what it shows, and the purpose of each precaution (boiled water, oil layer, anhydrous calcium chloride, cleaning metal strips with sandpaper).

Tricks to remember Metals and Non-metals

Short memory aids. Say each one aloud once, then use it on a question the same day.

Reactivity series in order
'Please Send Cats, Monkeys And Zebras In Large Hired Cages, Make Sure Guarded': K, Na, Ca, Mg, Al, Zn, Fe, Pb, H, Cu, Hg, Ag, Au.
Use it when: Write it in the margin before any displacement, acid or extraction question.
Extraction by position in the series
Top five (K to Al): electricity. Middle (Zn, Fe, Pb): carbon. Bottom (Hg, Cu from Cu2S, Ag, Au): heat alone or found native.
Use it when: In case-based metallurgy questions, choose the method from where the metal sits in the series.
Roasting vs calcination
Roasting has an 'S' sound for sulphide and uses lots of air. Calcination has a 'C' for carbonate and uses a little air.
Use it when: Stops you swapping the two processes and their air conditions.
Refining set-up
'Dirty donates, pure collects': the impure anode gives metal, the pure cathode collects it. Positive ions head to the negative cathode.
Use it when: Labelling the electrolytic refining diagram correctly.
Water ladder
Na and K: cold water and fire. Ca: cold water and floats. Mg: hot water and floats. Al, Zn, Fe: steam and give the oxide. Pb, Cu, Ag, Au: no reaction.
Use it when: Identifying unknown metals from how they react with water.
Amphoteric pair
'A-Z both ways': Aluminium oxide and Zinc oxide react with both acids and bases.
Use it when: MCQs and assertion-reason items on types of oxides.

Metals and Non-metals: board-level solved questions

Ordered from board level to HOTS. Cover the solution, write your own, then compare step by step.

Example 1: Ranking unknown metals from a displacement table · 1 mark · MCQHarder board level

Suppose metals P, Q and R are added separately to solutions of zinc sulphate, iron(II) sulphate, copper(II) sulphate and silver nitrate. P displaces the metal from iron(II) sulphate, copper(II) sulphate and silver nitrate, but not from zinc sulphate. Q displaces only silver from silver nitrate. R displaces the metal from all four solutions. Which statement is correct?
(a) R > P > Q, and Q can displace hydrogen from dilute hydrochloric acid.
(b) R > P > Q, and P can displace hydrogen from dilute hydrochloric acid.
(c) P > R > Q, and R can displace hydrogen from dilute hydrochloric acid.
(d) R > Q > P, and Q cannot displace hydrogen from dilute hydrochloric acid.

Try it first, then show the solutionSolution

R displaces all four metals (even zinc), P displaces three and Q displaces one. So the order is R > P > Q, which rules out (c) and (d).
P displaces iron, so P is above iron, and iron is above hydrogen in the activity series. So P can displace hydrogen from dilute HCl.
Q displaces silver but not copper, so Q lies below copper, which is below hydrogen. Q cannot displace hydrogen, which rules out (a).

Answer: (b) R > P > Q, and P can displace hydrogen from dilute hydrochloric acid.

Example 2: Why carbon cannot give aluminium · 1 mark · Assertion-reasonHarder board level

Assertion (A): Aluminium cannot be obtained by heating aluminium oxide with carbon.
Reason (R): Aluminium is used to reduce iron(III) oxide in the thermit reaction because it is more reactive than iron.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.

Try it first, then show the solutionSolution

A is true: aluminium is near the top of the activity series and has more affinity for oxygen than carbon, so carbon cannot remove oxygen from aluminium oxide. Aluminium is obtained by electrolytic reduction of aluminium oxide.
R is true: in $F e_{2} O_{3} + 2 A l \to 2 F e + A l_{2} O_{3}$ + heat, the more reactive aluminium displaces iron.
But R compares aluminium with iron and says nothing about aluminium and carbon. The real explanation of A is aluminium's greater affinity for oxygen than carbon's, so R does not explain A.

Answer: (b) Both A and R are true but R is not the correct explanation of A.

Example 3: Equations with water, steam and acid · 3 marks · Short answerBoard level

Write balanced chemical equations with state symbols for the following. Also state one observation for (a).
(a) Potassium is dropped into cold water.
(b) Steam is passed over heated aluminium.
(c) Iron filings are added to dilute sulphuric acid. (3 marks)

Try it first, then show the solutionSolution

(a) $2 K (s) + 2 H_{2} O (l) \to 2 K O H (a q) + H_{2} (g) + heat energy$
Observation: the reaction is violent and so exothermic that the hydrogen evolved catches fire.
(b) Aluminium does not react with cold or hot water, only with steam: $2 A l (s) + 3 H_{2} O (g) \to A l_{2} O_{3} (s) + 3 H_{2} (g)$
(c) Iron is above hydrogen, so it displaces hydrogen from the acid: $F e (s) + H_{2} S O_{4} (a q) \to F e S O_{4} (a q) + H_{2} (g)$

Answer: (a) $2 K + 2 H_{2} O \to 2 K O H + H_{2}$ ; hydrogen catches fire. (b) $2 A l + 3 H_{2} O (g) \to A l_{2} O_{3} + 3 H_{2}$ (c) $F e + H_{2} S O_{4} \to F e S O_{4} + H_{2}$

Example 4: Thermit reaction and redox · 3 marks · Short answerHarder board level

(a) Manganese dioxide is heated with aluminium powder. Write the balanced equation and identify the substance oxidised and the substance reduced.
(b) Why are the metals in such reactions produced in the molten state?
(c) Write the equation for the thermit reaction and give one use of it. (3 marks)

Try it first, then show the solutionSolution

(a) $3 M n O_{2} (s) + 4 A l (s) \to 3 M n (l) + 2 A l_{2} O_{3} (s) + heat$
Aluminium gains oxygen to form $A l_{2} O_{3}$ , so Al is oxidised; $M n O_{2}$ loses oxygen, so it is reduced. Aluminium, being more reactive, acts as the reducing agent.
(b) These displacement reactions are highly exothermic; the heat given out is so large that the metal formed melts.
(c) $F e_{2} O_{3} (s) + 2 A l (s) \to 2 F e (l) + A l_{2} O_{3} (s) + heat$
Use: joining railway tracks or repairing cracked machine parts.

Answer: (a) $3 M n O_{2} + 4 A l \to 3 M n + 2 A l_{2} O_{3}$ ; Al oxidised, $M n O_{2}$ reduced. (b) Large heat released melts the metal. (c) $F e_{2} O_{3} + 2 A l \to 2 F e + A l_{2} O_{3}$ ; used to join railway tracks.

Example 5: Extracting metals low in the activity series · 5 marks · Long answerBoard level

(a) Why are gold and silver often found in the free state in nature, while sodium is never found free? (1)
(b) Name the ore of mercury with its formula. Write the two balanced equations by which mercury is obtained from it. (2)
(c) Copper is found as $C u_{2} S$ . Write the two equations by which copper is obtained just by heating it in air. (1)
(d) Why are the ores of many metals oxides? (1) (5 marks)

Try it first, then show the solutionSolution

(a) Gold and silver are at the bottom of the activity series and are very unreactive, so they stay uncombined. Sodium is near the top and is so reactive that it is always found combined.
(b) Ore: cinnabar, $H g S$ .
Heated in air it changes to mercuric oxide: $2 H g S (s) + 3 O_{2} (g) heat 2 H g O (s) + 2 S O_{2} (g)$
Further heating reduces the oxide: $2 H g O (s) heat 2 H g (l) + O_{2} (g)$
(c) $2 C u_{2} S + 3 O_{2} (g) heat 2 C u_{2} O (s) + 2 S O_{2} (g)$ and then $2 C u_{2} O + C u_{2} S heat 6 C u (s) + S O_{2} (g)$
(d) Oxygen is a very reactive element and is very abundant on the earth, so many metals occur combined with it.

Answer: Unreactive metals stay free; mercury from cinnabar by $2 H g S + 3 O_{2} \to 2 H g O + 2 S O_{2}$ then $2 H g O \to 2 H g + O_{2}$ ; copper by $2 C u_{2} S + 3 O_{2} \to 2 C u_{2} O + 2 S O_{2}$ then $2 C u_{2} O + C u_{2} S \to 6 C u + S O_{2}$ ; oxide ores are common because oxygen is reactive and abundant.

Example 6: Alloys and protecting iron · 5 marks · Long answerBoard level

(a) What is an alloy? How is it prepared? (1)
(b) Why is pure iron not used, and what does adding a small amount of carbon do? (1)
(c) Name the metals mixed with iron to make stainless steel and state its useful property. (1)
(d) A galvanised iron sheet stays rust-free even after its zinc coating gets scratched. Explain. (1)
(e) Why is solder used to join electrical wires, and why is brass not used for wiring? (1) (5 marks)

Try it first, then show the solutionSolution

(a) An alloy is a uniform blend of a metal with one or more other elements, which may be metals or non-metals. To make it, the main metal is melted, the other elements are dissolved in it in fixed proportions, and the melt is cooled to room temperature.
(b) Pure iron is very soft and stretches easily when hot. Mixing about 0.05% carbon makes it hard and strong.
(c) Nickel and chromium; stainless steel is hard and does not rust.
(d) Galvanising coats iron with zinc. Zinc is more reactive than iron, so where the coating is broken, the zinc still reacts with air and moisture first and the iron is protected.
(e) Solder (lead and tin) has a low melting point, so it melts easily to join wires. The conductivity of an alloy is less than that of the pure metal, so brass conducts poorly and copper is used for circuits.

Answer: An alloy is a uniform blend made by melting the main metal and dissolving other elements in it; carbon makes iron hard and strong; nickel and chromium give rust-free stainless steel; more reactive zinc protects iron even when scratched; solder melts easily, while brass conducts less well than copper.

Example 7: Interpreting a heat-conduction experiment · 3 marks · Short answerHOTS / competency

Imagine two students fix a small wax-stuck pin at the end of four rods of equal length and thickness, made of silver, copper, aluminium and iron. The other ends are heated together at one centre. The pins fall after these times (hypothetical data): silver 40 s, copper 50 s, aluminium 90 s, iron 150 s.
(a) Arrange the metals in decreasing order of heat conduction.
(b) Why must the rods be of equal length and thickness?
(c) None of the rods melts. What does this show?
(d) If a lead rod were added, would you expect its pin to fall early or late? Give a reason from your textbook. (3 marks)

Try it first, then show the solutionSolution

(a) The faster the pin falls, the faster heat reached the wax. So: silver > copper > aluminium > iron.
(b) So that only the metal changes; a longer or thinner rod would itself change the time and the test would not be fair.
(c) Metals have high melting points.
(d) Late: lead is a comparatively poor conductor of heat, so heat would take longer to reach the wax.

Answer: (a) Silver > copper > aluminium > iron (b) To make it a fair test with only the metal changed (c) Metals have high melting points (d) Late, as lead is a poor conductor of heat.

Example 8: Identify the mystery metal · 3 marks · Short answerHOTS / competency

A metal M does not react with cold or hot water, but when steam is passed over hot M it forms an oxide of formula $M_{3} O_{4}$ and a gas that burns with a pop. M displaces copper from copper sulphate solution but does not displace zinc from zinc sulphate solution.
(a) Identify M and write the equation of its reaction with steam.
(b) Place M in the activity series relative to zinc and copper.
(c) M occurs in nature mainly as its oxide. Which method is used to extract it: heating alone, reduction with carbon, or electrolysis? Justify. (3 marks)

Try it first, then show the solutionSolution

Reacting only with steam, forming an $M_{3} O_{4}$ oxide and hydrogen (burns with a pop), matches iron.
(a) $3 F e (s) + 4 H_{2} O (g) \to F e_{3} O_{4} (s) + 4 H_{2} (g)$
(b) It displaces copper but not zinc, so Zn > Fe > Cu.
(c) Iron is in the middle of the activity series (moderately reactive), so its oxide is reduced by heating with a reducing agent such as carbon (coke). Heating alone works only for metals low in the series; electrolysis is needed only for the most reactive metals.

Answer: (a) M is iron: $3 F e + 4 H_{2} O (g) \to F e_{3} O_{4} + 4 H_{2}$ (b) Zn > Fe > Cu (c) Reduction with carbon, because iron is in the middle of the activity series.

Example 9: From electron configuration to extraction · 5 marks · Long answerHarder board level

Element X has electronic configuration 2, 8, 8, 2 and element Y has 2, 8, 7. (5 marks)
(a) Identify X and Y, say which is the metal, and write the formula of the compound they form. (1)
(b) Show the formation of this compound by transfer of electrons and name the ions. (1)
(c) The compound melts at 1045 K. Explain why its melting point is so high, and state whether it conducts electricity as a solid and when molten. (1)
(d) Write the equation for X with cold water. Why does X float, and why does the hydrogen not catch fire? (1)
(e) Why can X not be obtained by heating its oxide with carbon? How is it obtained, and what are the electrode reactions? (1)

Try it first, then show the solutionSolution

(a) X is calcium (atomic number 20) and Y is chlorine (atomic number 17). Calcium, with 2 valence electrons, is the metal. It gives one electron to each of two chlorine atoms, so the formula is $C a C l_{2}$ . (1 mark)
(b) $C a \to C a^{2 +} + 2 e^{-}$ (2, 8, 8) and $2 C l + 2 e^{-} \to 2 C l^{-}$ (each 2, 8, 8). Ions: calcium ion $C a^{2 +}$ and chloride ion $C l^{-}$ . (1 mark)
(c) The oppositely charged ions attract strongly, so a lot of energy is needed to separate them. The solid does not conduct because its ions are fixed in a rigid structure; the molten compound conducts because its ions move freely. (½ + ½ mark)
(d) $C a (s) + 2 H_{2} O (l) \to C a (O H)_{2} (a q) + H_{2} (g)$ . Hydrogen bubbles stick to the calcium and make it float; the reaction is less violent than sodium's, so the heat given out is not enough to ignite the hydrogen. (½ + ½ mark)
(e) Calcium is near the top of the activity series and has more affinity for oxygen than carbon, so carbon cannot reduce its oxide. It is obtained by electrolysis of molten calcium chloride: cathode $C a^{2 +} + 2 e^{-} \to C a$ ; anode $2 C l^{-} \to C l_{2} + 2 e^{-}$ . (½ + ½ mark)

Answer: X = calcium (the metal), Y = chlorine; compound $C a C l_{2}$ with ions $C a^{2 +}$ and $C l^{-}$ . High melting point from strong inter-ionic attraction; conducts when molten, not as a solid. $C a + 2 H_{2} O \to C a (O H)_{2} + H_{2}$ ; it floats on hydrogen bubbles. Calcium is extracted by electrolysis of molten $C a C l_{2}$ , because carbon cannot reduce its oxide.

Example 10: Tracking copper from ore to wire · 5 marks · Long answerHarder board level

A reddish-brown metal M occurs in nature as $M_{2} S$ . It gives no bubbles with dilute hydrochloric acid, and it is deposited on an iron nail placed in a solution of its sulphate. (5 marks)
(a) Identify M and explain its position relative to hydrogen and iron in the activity series. (1)
(b) Write the two equations by which M is obtained from $M_{2} S$ by heating in air. Why is carbon not needed? (1)
(c) Write the equation for the reaction on the iron nail and name the type of reaction. (1)
(d) The metal obtained is impure. State the anode, cathode and electrolyte used to refine it, and where the impurities go. (1)
(e) Why is pure M, and not brass, used for electrical wiring? (1)

Try it first, then show the solutionSolution

(a) M is copper. No reaction with dilute HCl shows it is below hydrogen; being displaced by iron shows it is below iron. (1 mark)
(b) $2 C u_{2} S + 3 O_{2} (g) heat 2 C u_{2} O (s) + 2 S O_{2} (g)$ , then $2 C u_{2} O + C u_{2} S heat 6 C u (s) + S O_{2} (g)$ . Copper is low in the activity series, so heating alone is enough and no reducing agent such as carbon is needed. (½ + ½ mark)
(c) $F e (s) + C u S O_{4} (a q) \to F e S O_{4} (a q) + C u (s)$ ; a displacement reaction. (½ + ½ mark)
(d) Anode: impure copper; cathode: thin strip of pure copper; electrolyte: acidified copper sulphate solution. Soluble impurities go into the solution; insoluble impurities settle below the anode as anode mud. (½ + ½ mark)
(e) An alloy conducts electricity less well than the pure metal. Brass, an alloy of copper and zinc, is a poorer conductor, so pure copper is used for circuits. (1 mark)

Answer: M is copper, below iron and hydrogen. It is obtained from $C u_{2} S$ by heating in air ( $2 C u_{2} S + 3 O_{2} \to 2 C u_{2} O + 2 S O_{2}$ , then $2 C u_{2} O + C u_{2} S \to 6 C u + S O_{2}$ ). Iron displaces it: $F e + C u S O_{4} \to F e S O_{4} + C u$ . It is refined with an impure copper anode, pure copper cathode and acidified copper sulphate electrolyte. Pure copper is used for wiring because brass conducts less well.

Case-study practice (Section E style)

Read the situation, then answer every part. In the board paper this is a 4-mark question split into 1 + 1 + 2 marks.

Refining copper in a small workshop

Suppose a small workshop buys impure copper and refines it before making electrical wire. A thick plate of impure copper and a thin strip of pure copper hang in a tank of acidified copper sulphate solution, joined to a battery. Imagine that in one run the workers record (hypothetical data): the impure plate loses 1.00 kg, the pure strip gains 0.96 kg, and 0.03 kg of sludge collects at the bottom of the tank. The colour of the solution stays about the same throughout. The owner wants to know where all the mass went and how pure the original plate was.

(i) · 1 mark
Which plate is the anode and which is the cathode?
Answer
Answer: Anode: the impure copper plate. Cathode: the thin strip of pure copper.
The impure metal must dissolve, so it is made the anode (joined to +). Pure copper is deposited on the cathode (joined to −).
(ii) · 1 mark
What is the sludge at the bottom called, and what is it made of?
Answer
Answer: Anode mud: the insoluble impurities from the impure copper.
Insoluble impurities do not dissolve and settle down below the anode; this deposit is called anode mud.
(iii) · 2 marks
Account for the 1.00 kg lost by the anode, and find the percentage of copper in the impure plate.
Answer
Answer: 0.96 kg is pure copper, 0.03 kg is anode mud and 0.01 kg is soluble impurities in the solution; the plate was 96% copper.
An equivalent amount of pure copper goes from the anode to the cathode, so 0.96 kg of the anode was copper. Insoluble impurities = 0.03 kg (anode mud). Remaining 1.00 − 0.96 − 0.03 = 0.01 kg are soluble impurities that went into the solution. Purity = (0.96 ÷ 1.00) × 100 = 96%.

Choosing the right alloy

Imagine a hardware shop owner keeps a card of notes for customers. It says: pure iron is very soft and stretches easily when hot; iron with a little carbon (about 0.05%) is hard and strong; iron mixed with nickel and chromium is hard and does not rust; brass (copper and zinc) and bronze (copper and tin) conduct electricity less well than pure copper; solder (lead and tin) melts at a low temperature. The card also notes that an alloy made with mercury has a special name. Customers come in with different jobs.

(i) · 1 mark
A customer wants a strong frame for a gate. Should it be made of pure iron or of iron with about 0.05% carbon? Why?
Answer
Answer: Iron with about 0.05% carbon.
Pure iron is very soft and stretches when hot. A small amount of carbon makes iron hard and strong, which a gate frame needs.
(ii) · 1 mark
An electrician wants to join two electrical wires. Which alloy on the card should he use, and which property makes it suitable?
Answer
Answer: Solder, because it has a low melting point.
Solder (lead and tin) melts at a low temperature, so it can be melted easily and used to join the wires.
(iii) · 1 mark
A customer asks for brass wire for house wiring because brass looks shiny. Advise him, using the card.
Answer
Answer: Use copper wire, not brass.
An alloy conducts electricity less well than the pure metal. Brass conducts less well than copper, so copper is the right choice for carrying current.
(iv) · 1 mark
A cutlery maker wants spoons that do not rust. Which alloy should she use and what is it made of? What name is given to an alloy in which one metal is mercury?
Answer
Answer: Stainless steel (iron with nickel and chromium); an amalgam.
Stainless steel is hard and does not rust, so it suits spoons that are washed every day (½ mark). An alloy containing mercury is called an amalgam (½ mark).

Which metal takes the oxygen?

Suppose a student heats dry mixtures of a metal oxide and a metal powder, one pair at a time, under her teacher's supervision, and records these results. Copper(II) oxide with zinc: reacts, and reddish-brown copper forms. Zinc oxide with copper: no change. Iron(III) oxide with aluminium: very vigorous reaction, a lot of heat, and molten iron forms. Manganese dioxide with aluminium: vigorous reaction, and molten manganese forms. Magnesium oxide with aluminium: no change.

(i) · 1 mark
Using only these results, which is more reactive, magnesium or aluminium? Justify.
Answer
Answer: Magnesium.
Aluminium takes oxygen from iron(III) oxide and manganese dioxide but not from magnesium oxide. So magnesium holds on to oxygen more strongly than aluminium, which means magnesium is more reactive.
(ii) · 1 mark
Write the balanced equation for the reaction of iron(III) oxide with aluminium, name the reaction and give one use.
Answer
Answer: $F e_{2} O_{3} (s) + 2 A l (s) \to 2 F e (l) + A l_{2} O_{3} (s)$ + heat; the thermit reaction; used to join railway tracks.
Atom check: Fe 2 = 2, O 3 = 3, Al 2 = 2 (½ mark). It is the thermit reaction, used to join railway tracks or cracked machine parts (½ mark).
(iii) · 1 mark
In the manganese dioxide reaction, write the balanced equation and identify the substance oxidised and the substance reduced.
Answer
Answer: $3 M n O_{2} (s) + 4 A l (s) \to 3 M n (l) + 2 A l_{2} O_{3} (s)$ + heat; aluminium is oxidised and manganese dioxide is reduced.
Atom check: Mn 3 = 3, O 6 = 6, Al 4 = 4 (½ mark). Aluminium gains oxygen, so it is oxidised; $M n O_{2}$ loses oxygen, so it is reduced (½ mark).
(iv) · 1 mark
The student predicts that copper powder will reduce iron(III) oxide when heated. Is she right? Explain using the activity series.
Answer
Answer: No, copper cannot reduce iron(III) oxide.
Copper is below iron in the activity series, so it cannot take oxygen from the oxide of the more reactive iron. Her own result with zinc oxide and copper shows the same pattern: copper cannot reduce the oxide of a more reactive metal.

Where the marks are

How a typical answer is split into step marks. Show every step: a right final answer alone rarely earns full marks.

Write balanced chemical equations for the reaction of aluminium oxide with (i) dilute hydrochloric acid and (ii) sodium hydroxide solution. What do these two reactions show about the nature of aluminium oxide? (2 marks) (2 marks)

Step	Marks
Balanced equation with acid: $A l_{2} O_{3} + 6 H C l \to 2 A l C l_{3} + 3 H_{2} O$	0.5
Balanced equation with base: $A l_{2} O_{3} + 2 N a O H \to 2 N a A l O_{2} + H_{2} O$	0.5
Product with the base named as sodium aluminate, and both reactions shown to give a salt and water	0.5
Conclusion: aluminium oxide reacts with both acids and bases, so it is an amphoteric oxide	0.5

A clean iron nail is dipped in copper sulphate solution and left for about 20 minutes. (a) State two observations. (b) Write the balanced equation with state symbols. (c) Name the type of reaction and state what it tells you about iron and copper. (3 marks) (3 marks)

Step	Marks
Observation 1: a reddish-brown coating of copper forms on the iron nail	0.5
Observation 2: the blue colour of the solution fades (turns pale green)	0.5
Equation: $F e (s) + C u S O_{4} (a q) \to F e S O_{4} (a q) + C u (s)$	1
Type: displacement reaction	0.5
Inference: iron is more reactive than copper, so it displaces copper from its salt solution	0.5

(a) Write the electronic configurations of magnesium (atomic number 12) and chlorine (atomic number 17). (b) Show the formation of magnesium chloride by the transfer of electrons. (c) Name the cation and anion present. (d) Give reasons: (i) magnesium chloride has a high melting point; (ii) it is soluble in water but not in kerosene; (iii) it conducts electricity in molten state but not as a solid. (5 marks) (5 marks)

Step	Marks
Configurations: Mg = 2, 8, 2 and Cl = 2, 8, 7	0.5
Mg loses two electrons: $M g \to M g^{2 +} + 2 e^{-}$ (2, 8, 2 becomes 2, 8)	0.5
Each of two chlorine atoms gains one electron: $C l + e^{-} \to C l^{-}$ (2, 8, 7 becomes 2, 8, 8), giving $M g C l_{2}$	1
Ions named: magnesium cation $M g^{2 +}$ and chloride anion $C l^{-}$	0.5
High melting point: strong electrostatic attraction between oppositely charged ions needs a lot of energy to break	1
Solubility: ionic (electrovalent) compounds are generally soluble in water and insoluble in kerosene and petrol	0.5
Conduction: in the solid the ions are held in a rigid structure and cannot move; on melting, heat overcomes the attraction, the ions move freely and carry current	1

Where students lose marks in Metals and Non-metals

The slips examiners see most often, and what to write instead.

Mistake: Predicting a displacement that cannot happen
Students remember that metals react with salts but forget to check positions in the reactivity series.
Wrong working
$C u + F e S O_{4} \to C u S O_{4} + F e$
Right working
No reaction occurs: copper is below iron in the reactivity series, so it cannot displace iron.
Do this: Before writing any displacement equation, find both metals in the series. Only a higher metal displaces a lower one.
Usually costs: Usually the full 1 mark in an MCQ, or 1 to 2 marks in a short answer.
Mistake: Swapping the conditions for roasting and calcination
Both involve strong heating and both give an oxide, so the details blur.
Wrong working
Calcination: $Z n S$ heated in excess air gives ZnO.
Right working
Roasting: $2 Z n S + 3 O_{2} heat 2 Z n O + 2 S O_{2}$ (excess air). Calcination: $Z n C O_{3} heat Z n O + C O_{2}$ (limited air).
Do this: Link sulphide with roasting and excess air; carbonate with calcination and limited air.
Usually costs: About 1 to 2 marks in a case-based or long answer.
Mistake: Unbalanced or wrong-product equations for metals with water or steam
Students copy the sodium pattern (hydroxide) for iron, or skip the atom count.
Wrong working
$F e + H_{2} O \to F e (O H)_{2} + H_{2}$
Right working
$3 F e (s) + 4 H_{2} O (g) \to F e_{3} O_{4} (s) + 4 H_{2} (g)$
Do this: Remember that metals reacting with steam give the oxide. Count Fe, H and O on both sides before moving on.
Usually costs: ½ to 1 mark per equation.
Mistake: Reversing the electrodes in electrolytic refining
Students think the pure metal should be where the current 'starts'.
Wrong working
Anode: pure copper strip; cathode: impure copper block.
Right working
Anode (+): impure copper. Cathode (−): thin strip of pure copper. Electrolyte: acidified copper sulphate. Pure copper deposits on the cathode.
Do this: Positive metal ions move to the negative electrode, so the pure metal builds up on the cathode.
Usually costs: 1 to 2 marks of a 3-mark diagram question.
Mistake: Saying solid ionic compounds conduct electricity
Students know ionic compounds contain ions and assume ions always mean conduction.
Wrong working
Sodium chloride conducts in all states because it is made of ions.
Right working
Solid NaCl does not conduct, because its ions are fixed in a rigid structure. It conducts when molten or dissolved in water, because the ions can then move.
Do this: Always say whether the ions are free to move in the state you are describing.
Usually costs: 1 mark in a reasons question; the full mark in an assertion-reason item.
Mistake: Incomplete conclusion from the rusting experiment
Students look only at tube A and miss what tubes B and C prove.
Wrong working
Iron rusts in water.
Right working
Iron rusts only when both air and water are present: B (no air) and C (no moisture) show no rust, while A (both present) rusts.
Do this: Name both conditions and use tubes B and C as the evidence.
Usually costs: About 1 mark.
Mistake: Writing hydrogen gas as a product with nitric acid
Students apply 'metal + acid gives salt + hydrogen' to every acid.
Wrong working
Zinc and dilute nitric acid give zinc nitrate and hydrogen.
Right working
Hydrogen is generally not evolved, because nitric acid is a strong oxidising agent: it oxidises H2 to water and is itself reduced to nitrogen oxides. Only Mg and Mn give H2, and only with very dilute HNO3.
Do this: Treat nitric acid as the exception and remember the Mg/Mn note.
Usually costs: The 1 mark in an MCQ or assertion-reason item.

NCERT exercise guide: Metals and Non-metals

What each exercise in the NCERT chapter tests, how to approach it, and a question of the same kind solved step by step. Questions here are written in our own words.

In-text questions after section 3.1 (Physical Properties)

What it tests: Examples of metals and non-metals that break the general rules (liquid metal, soft metals, best and poor conductors of heat) and the meanings of malleability and ductility.

How to approach it: Learn the exceptions as a short list, because these questions ask for one named example each. When defining a property, say what the metal can be made into (sheets or wires) and give one example.

Mirrors the 'give an example of an element which...' type

Name: (i) a metal that melts if kept on your palm; (ii) a non-metal that is lustrous; (iii) the hardest natural substance; (iv) a non-metal that conducts electricity; (v) the most ductile metal.

Show the solutionSolution

(i) Gallium (or caesium) has a very low melting point, so body heat is enough to melt it.
(ii) Iodine is a non-metal but has lustre.
(iii) Diamond, an allotrope of carbon, is the hardest natural substance.
(iv) Graphite, another allotrope of carbon, conducts electricity.
(v) Gold is the most ductile metal; about 2 km of wire can be drawn from one gram.

Answer: (i) Gallium or caesium (ii) Iodine (iii) Diamond (iv) Graphite (v) Gold

In-text questions after section 3.2 (Chemical Properties of Metals)

What it tests: Why reactive metals are stored in kerosene, equations of metals with steam, water and dilute acids, displacement from salt solutions, and ordering unknown metals from a results table.

How to approach it: For a results table, count how many solutions each metal displaces: the more it displaces, the higher it is. A metal that displaces nothing is the least reactive. Always write balanced equations with state symbols and say what you would see (colour change, deposit).

Mirrors the 'four unknown metals and a table of displacement results' type

Metals W, X, Y and Z are added separately to solutions of zinc sulphate, iron(II) sulphate, copper(II) sulphate and silver nitrate. W displaces the metal from all four solutions. X displaces from iron(II) sulphate, copper(II) sulphate and silver nitrate, but not from zinc sulphate. Y displaces only from silver nitrate. Z shows no reaction with any solution. (a) Which is the most reactive metal? (b) What would you see if X is added to copper(II) sulphate solution? (c) Arrange W, X, Y and Z in decreasing order of reactivity. (d) Between which two metals of the activity series does X lie?

Show the solutionSolution

A metal displaces another only if it is more reactive than the metal in the salt.
W displaces zinc, so it is more reactive than zinc, iron, copper and silver: it is the most reactive.
X displaces iron, copper and silver but not zinc, so it lies below zinc and above iron.
Y displaces only silver, so it lies below copper but above silver.
Z displaces nothing, so it is below silver.
With copper(II) sulphate, X pushes out copper: a reddish-brown deposit forms on X and the blue colour of the solution fades.

Answer: (a) W (b) Reddish-brown copper deposits on X and the blue colour fades. (c) W > X > Y > Z (d) X lies between zinc and iron.

In-text questions after section 3.3 (How do Metals and Non-metals React?)

What it tests: Electron-dot structures of metals and non-metals, formation of ionic compounds by electron transfer, naming the ions, and the reason for high melting points.

How to approach it: Start from the electronic configuration (use Table 3.3 values), decide how many electrons the metal loses and the non-metal gains, and balance them so the compound is neutral. Write charges on the ions. Link melting point to the strong attraction between ions.

Mirrors the 'show the formation of an ionic compound by transfer of electrons' type

Calcium has atomic number 20 and chlorine 17. (a) Write their electronic configurations. (b) Show the formation of calcium chloride by the transfer of electrons. (c) Name the ions present. (d) Calcium chloride melts at 1045 K. Why is its melting point so high?

Show the solutionSolution

Ca = 2, 8, 8, 2 and Cl = 2, 8, 7.
Calcium loses its two outermost electrons to reach a stable octet: $C a \to C a^{2 +} + 2 e^{-}$ (2, 8, 8).
One chlorine atom can take only one electron: $C l + e^{-} \to C l^{-}$ (2, 8, 8). So two chlorine atoms are needed for the two electrons from calcium.
The oppositely charged ions attract each other strongly and form $C a C l_{2}$ .
Ions present: calcium ion $C a^{2 +}$ and chloride ion $C l^{-}$ .
A large amount of energy is needed to overcome the strong inter-ionic attraction, so the melting point is high.

Answer: $C a C l_{2}$ forms when one Ca atom gives one electron to each of two Cl atoms; ions are $C a^{2 +}$ and $C l^{-}$ ; the melting point is high because of strong electrostatic attraction between the ions.

In-text questions after sections 3.4 and 3.5 (Occurrence of Metals, Corrosion)

What it tests: Definitions of mineral, ore and gangue, metals found free, the process for getting a metal from its oxide, displacement when metal oxides are heated with metals, metals that do not corrode easily, and alloys.

How to approach it: Give definitions in one precise sentence each, with the key difference: an ore is a mineral from which the metal can be extracted profitably. For 'oxide heated with metal' questions, use the activity series: only a more reactive metal can take oxygen from the oxide of a less reactive metal.

Mirrors the 'metal oxides heated with metals: where does displacement occur?' type

Three mixtures are heated: (i) copper(II) oxide with zinc, (ii) zinc oxide with copper, (iii) magnesium oxide with zinc. In which case does a displacement reaction take place? Write the balanced equation and name the substance reduced.

Show the solutionSolution

Order from the activity series: Mg > Zn > Cu.
(i) Zinc is more reactive than copper, so it removes oxygen from copper oxide: reaction occurs.
(ii) Copper is less reactive than zinc, so it cannot reduce zinc oxide: no reaction.
(iii) Zinc is less reactive than magnesium, so it cannot reduce magnesium oxide: no reaction.
Equation: $C u O (s) + Z n (s) heat Z n O (s) + C u (s)$
Copper(II) oxide loses oxygen, so it is reduced; zinc is oxidised.

Answer: Only (i) reacts: $C u O + Z n \to Z n O + C u$ . Copper(II) oxide is reduced to copper.

End-of-chapter exercises

What it tests: MCQs on displacement pairs and rust prevention, distinguishing metals from non-metals by tests, amphoteric oxides, metals that do and do not displace hydrogen, electrolytic refining, the oxide of sulphur, reasons-type questions on storage, utensils, ores and jewellery, and a comparison of chemical properties.

How to approach it: For 'give reasons' items, write the fact first, then the property that causes it, in two lines. For comparison questions, use a point-by-point list (oxides, acids, ions, hydrogen) with an example equation for each. For situation questions, decide what property of the metal the situation depends on.

Mirrors the 'identify the element from its reactions' type

An element E is a brittle solid that does not conduct electricity. It burns in air to form an oxide; the fumes dissolved in water turn blue litmus red. E does not give any gas with dilute hydrochloric acid. (a) Is E a metal or a non-metal? Give two reasons. (b) What is the nature of its oxide? (c) Why does E give no gas with dilute acid?

Show the solutionSolution

Brittleness and non-conduction of electricity are properties of non-metals.
Its oxide in water turns blue litmus red, so the oxide is acidic; metals give basic oxides.
So E is a non-metal and its oxide is acidic.
Non-metals do not displace hydrogen from dilute acids, so no hydrogen gas is given off.

Answer: (a) Non-metal: it is brittle, does not conduct, and forms an acidic oxide. (b) Acidic. (c) Non-metals cannot displace hydrogen from dilute acids.

Activity 3.11 (Metals with dilute hydrochloric acid)

What it tests: Comparing the rate of bubbling and the rise in temperature when clean metal samples are put in dilute HCl, and arranging the metals by reactivity.

How to approach it: Link two observations to reactivity: faster bubbles and a bigger rise in temperature mean a more reactive metal. Remember the safety point (no sodium or potassium) and the cleaning step (sandpaper removes the oxide layer).

Mirrors activity questions on Activity 3.11

In Activity 3.11, clean samples of magnesium, aluminium, zinc, iron and copper are put in test tubes of dilute hydrochloric acid with thermometers dipped in the acid. (a) Why are the samples rubbed with sandpaper first? (b) Which metal gives the fastest bubbling and highest temperature? (c) What do you see with copper and why? (d) Write the equation for zinc. (e) Why are sodium and potassium not used?

Show the solutionSolution

Sandpaper removes the oxide layer on the surface so the metal itself meets the acid.
Magnesium bubbles fastest and its reaction is the most exothermic, so its thermometer shows the highest temperature. Order: Mg > Al > Zn > Fe.
Copper shows no bubbles and no change in temperature, because copper is below hydrogen in the activity series and does not react with dilute HCl.
$Z n (s) + 2 H C l (a q) \to Z n C l_{2} (a q) + H_{2} (g)$
Sodium and potassium react vigorously even with cold water, so they are unsafe with aqueous acid.

Answer: (a) To remove the oxide layer. (b) Magnesium. (c) No reaction, as copper is below hydrogen. (d) $Z n + 2 H C l \to Z n C l_{2} + H_{2}$ (e) They react too violently.

Metals and Non-metals: previous year questions

Asked in 21 of the 21 board papers we hold (2023 to 2026), on average 6.5 marks per paper; 76 questions in all, counting OR alternatives. In 4 of 4 sample papers.

Counted from the real papers on our previous year papers page, not estimated. Average marks are over every board paper we hold, with an OR pair counted once. Chapter tags are ours.

Solved board questions from Metals and Non-metals

Real questions from recent papers. Try each one first, then open our step-by-step solution with marks per step.

2026, set 31/1/1, Q21 · 1 mark · MCQ

Which of the following is a poor conductor of electricity?

(A)Pb
(B)Cu
(C)Ag
(D)Al

Try it first, then show our solutionSolution

Silver, copper and aluminium are the best conductors of electricity.
Lead (Pb) and mercury are comparatively poor conductors. Correct option: (A) Pb.
1 mark

Answer: Pb, option (A)

Where the marks are

Identifies lead as the poor conductor (1 mark)

See it in the full 2026 board paper, set 31/1/1

2026, set 31/1/1, Q28 · 4 marks · Case-basedCompetency-based

Read the following passage and answer the questions given below:
Most of metals occur in combined state in form of ores. Carbonate ores are converted into oxides by calcination and sulphide ores by roasting. Oxides are reduced with suitable reducing agent like carbon to get free metal. Highly reactive metals like – Al, Mg are also used as reducing agents to obtain metal from their oxides. Most reactive metals are obtained by electrolytic reduction of their molten ores. Alloying is a very good method of improving the properties of a metal. We can get desired properties by this method. The electrical conductivity and melting point of an alloy is less than that of pure metals.

(a)
Why carbonate or sulphide ores are converted to oxides before extraction of metal from it?
1 mark
(b)
Write a reaction in which Aluminium is used as a reducing agent to obtain metal from its oxide.
1 mark
(c)(i)
How is copper obtained from its ore (Cu₂S)? Give equations of the reactions.
2 marks
(c)(ii)(I)
Why highly reactive metals cannot be obtained from their oxides by using carbon as a reducing agent?
1 mark
(c)(ii)(II)
Why solder, an alloy of lead and tin, is used for welding electrical wires together?
1 mark

Try it first, then show our solutionSolution

(a) It is easier to obtain a metal from its oxide than from its carbonate or sulphide, because a metal oxide can be reduced readily by carbon. So carbonate ores are calcined and sulphide ores are roasted to convert them into oxides first.
1 mark
(b) Thermit reaction: $F e_{2} O_{3} (s) + 2Al (s) \to 2Fe (l) + A l_{2} O_{3} (s) + heat$
1 mark
(c)(i) Copper glance ( $C u_{2} S$ ) is roasted in air, which converts part of it to copper(I) oxide: $2 C u_{2} S + 3 O_{2} heat 2 C u_{2} O + 2 S O_{2}$
1 mark
(c)(i) The $C u_{2} O$ formed then reacts with the remaining $C u_{2} S$ (self-reduction) to give copper metal: $2 C u_{2} O + C u_{2} S heat 6 Cu + S O_{2}$
1 mark
(c)(ii)(I) [OR alternative] Highly reactive metals such as Na, Mg and Al have a greater affinity for oxygen than carbon has. So carbon cannot remove oxygen from their oxides, and these metals are obtained by electrolytic reduction instead.
1 mark
(c)(ii)(II) [OR alternative] Solder has a low melting point, lower than that of the pure metals lead and tin. So it melts easily and can be used to join electrical wires.
1 mark

Answer: (a) Oxides are easier to reduce to metal; (b) Fe₂O₃ + 2Al → 2Fe + Al₂O₃ + heat; (c)(i) 2Cu₂S + 3O₂ → 2Cu₂O + 2SO₂, then 2Cu₂O + Cu₂S → 6Cu + SO₂; OR (c)(ii) (I) these metals have more affinity for oxygen than carbon; (II) solder has a low melting point

Where the marks are

Oxides are easier to reduce to metal (1 mark)
Any correct thermit-type equation (1 mark)
Roasting equation for Cu₂S (1 mark)
Self-reduction equation giving Cu (1 mark)
OR: greater affinity for oxygen than carbon (1 mark); low melting point of solder (1 mark)

See it in the full 2026 board paper, set 31/1/1

2026, set 31/2/1, Q25 · 2 marks · Very short answerCompetency-based

Read the following passage and answer the questions that follow :

One student was comparing the reactivity of different metals for his science project. He added iron filings in four test tubes A, B, C and D containing aqueous solutions of $Z n S O_{4}$ , $C u S O_{4}$ , $F e S O_{4}$ and $A l_{2} (S O_{4})_{3}$ .

(i)
In which of the test tubes will he observe the reaction to be the most vigorous and why ?
1 mark
(ii)
Write a balanced equation for the reaction involved.
1 mark

Try it first, then show our solutionSolution

(i) The reaction occurs in test tube B ( $C u S O_{4}$ solution).
½ mark
Reason: iron is more reactive than copper, so it displaces copper from copper sulphate solution. Iron is less reactive than Zn and Al and cannot displace itself from $F e S O_{4}$ , so no reaction occurs in A, C and D.
½ mark
(ii) $F e (s) + C u S O_{4} (a q) \to F e S O_{4} (a q) + C u (s)$
The blue solution turns pale green and reddish-brown copper is deposited.
1 mark

Answer: (i) Test tube B, as iron is more reactive than copper and displaces it; (ii) $F e (s) + C u S O_{4} (a q) \to F e S O_{4} (a q) + C u (s)$

Where the marks are

Identifies test tube B (½ mark)
Reason: Fe is more reactive than Cu and displaces it (½ mark)
Correct balanced equation (1 mark)

See it in the full 2026 board paper, set 31/2/1

Every Metals and Non-metals question, by year

For 2027

Sample paper 2026-27: Q23 (1 mark, solved), Q28 (4 marks, solved)

2026

Set 31/1/1: Q21 (1 mark, solved), Q23 (1 mark, solved), Q28 (4 marks, solved)

Set 31/2/1: Q20 (1 mark, solved), Q23 (1 mark, solved), Q25 (2 marks, solved), Q26(a) (3 marks, solved), Q26(b) (3 marks, solved)

Set 31/3/1: Q23 (1 mark, solved), Q25 (2 marks, solved), Q28 (4 marks, solved)

Set 31/4/1: Q21 (1 mark, solved), Q22 (1 mark, solved), Q27(A) (3 marks, solved), Q27(B) (3 marks, solved)

Set 31/5/1: Q19 (1 mark, solved), Q23 (1 mark, solved), Q29(A) (5 marks, solved), Q29(B) (5 marks, solved)

Sample paper 2025-26: Q25 (2 marks, solved), Q26(A) (3 marks, solved), Q26(B) (3 marks, solved)

2025

Set 31/1/1: Q2 (1 mark, solved), Q5 (1 mark, solved), Q6 (1 mark, solved), Q7 (1 mark, solved), Q27 (3 marks, solved), Q28(a) (3 marks, solved), Q28(b) (3 marks, solved)

Set 31/2/1: Q4 (1 mark, solved), Q5 (1 mark, solved), Q17 (1 mark, solved), Q21 (2 marks, solved), Q28 (3 marks, solved)

Set 31/3/1: Q3 (1 mark, solved), Q17 (1 mark, solved), Q27 (3 marks, solved), Q34(a) (5 marks, solved), Q34(b) (5 marks, solved)

Set 31/4/1: Q3 (1 mark, solved), Q22(A) (2 marks, solved), Q22(B) (2 marks, solved), Q28 (3 marks, solved)

Set 31/5/1: Q2 (1 mark, solved), Q4 (1 mark, solved), Q6 (1 mark, solved), Q28(A) (3 marks, solved), Q28(B) (3 marks, solved)

Set 31/6/1: Q21 (2 marks, solved), Q37 (4 marks, solved)

Sample paper 2024-25: Q2 (1 mark, solved), Q5 (1 mark, solved), Q6 (1 mark, solved), Q17 (1 mark, solved), Q27(A) (3 marks, solved), Q27(B) (3 marks, solved)

2024

Set 31/1/1: Q3 (1 mark, solved), Q6 (1 mark, solved), Q17 (1 mark, solved), Q37 (4 marks, solved)

Set 31/2/1: Q5 (1 mark, solved), Q17 (1 mark, solved), Q28 (3 marks, solved)

Set 31/3/1: Q17 (1 mark, solved), Q27 (3 marks, solved), Q28(a) (3 marks, solved), Q28(b) (3 marks, solved)

Set 31/4/1: Q4 (1 mark, solved), Q17 (1 mark, solved), Q21(b) (2 marks, solved), Q37 (4 marks, solved)

Set 31/5/1: Q5 (1 mark, solved), Q28 (3 marks, solved)

Sample paper 2023-24: Q2 (1 mark, solved), Q4 (1 mark, solved), Q5 (1 mark, solved), Q6 (1 mark, solved), Q7 (1 mark, solved), Q27 (3 marks, solved), Q28(a) (3 marks, solved), Q28(b) (3 marks, solved)

2023

Set 31/1/1: Q5 (1 mark, solved), Q17 (1 mark, solved), Q37 (4 marks, solved)

Set 31/2/1: Q4 (1 mark, solved), Q5 (1 mark, solved), Q6 (1 mark, solved), Q28 (3 marks, solved)

Set 31/4/1: Q37 (4 marks, solved)

Set 31/5/1: Q37 (4 marks, solved)

Set 31/6/1: Q8 (1 mark, solved), Q28(b) (3 marks, solved), Q37 (4 marks, solved)

Practice questions on Metals and Non-metals

Write each answer on paper first. Open the hint only if you are stuck, and the answer only when you have finished.

Q1 · 1 mark · MCQHarder board level
Element X has electronic configuration 2, 8, 2. Which statement about X is correct?
(a) X forms $X^{2 +}$ ions and its oxide turns blue litmus red.
(b) X is extracted by heating its oxide with carbon.
(c) X forms a chloride $X C l_{2}$ that conducts electricity when molten.
(d) X reacts violently with cold water and the hydrogen catches fire.
Hint
Identify X first, then test each statement against a different part of the chapter.
Answer
(c) X forms a chloride $X C l_{2}$ that conducts electricity when molten. X is magnesium. Its oxide is basic, so (a) is wrong; it is extracted by electrolysis of its molten chloride, so (b) is wrong; it does not react with cold water, so (d) is wrong. $M g C l_{2}$ is ionic, and its ions move freely when molten.
Q2 · 2 marks · Very short answerBoard level
'Every ore is a mineral, but every mineral is not an ore.' Justify this statement. Why must gangue be removed before the metal is extracted? (2 marks)
Hint
Think of the word 'profitably'.
Answer
A mineral is any element or compound found naturally in the earth's crust. An ore is a mineral with a high enough percentage of a metal for the metal to be extracted profitably; minerals with too little of the metal are not ores. Gangue is the soil, sand and other impurities in a mined ore. It must be removed first so that the metal is extracted from the enriched ore and not from a large mass of impurities.
Q3 · 1 mark · Assertion-reasonHarder board level
Assertion (A): A galvanised iron article does not rust even where its zinc coating has been scratched.
Reason (R): Zinc forms a coating over the iron that keeps air and moisture away from it.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
Hint
Does a covering still work at the spot where it has been scratched off?
Answer
(b) A is true: a galvanised article stays protected even when the zinc coat is broken. R is true: the zinc coat does cover the iron. But a covering cannot protect the iron at a scratch, where the coat is missing. The protection there comes from zinc being more reactive than iron, so R does not explain A.
Q4 · 3 marks · Short answerBoard level
Using electron-dot structures, show the formation of sodium oxide from sodium (atomic number 11) and oxygen (atomic number 8). Name the ions and explain why two sodium atoms are needed. (3 marks)
Hint
How many electrons does oxygen need to complete its octet?
Answer
Na = 2, 8, 1 (one valence dot); O = 2, 6 (six valence dots). Each Na loses one electron: $N a \to N a^{+} + e^{-}$ . Oxygen needs two electrons: $O + 2 e^{-} \to O^{2 -}$ (2, 8). So two Na atoms each give one electron to one O atom, forming $N a_{2} O$ . Ions: $N a^{+}$ and $O^{2 -}$ (oxide ion).
Q5 · 3 marks · Short answerHarder board level
Give reasons: (a) The hydrogen produced when calcium reacts with water does not catch fire, but with sodium it does. (b) Calcium starts floating in water. (c) Magnesium also floats, but only in hot water. Write the equation for calcium with water. (3 marks)
Hint
Compare how much heat each reaction gives out.
Answer
(a) Sodium's reaction is violent and so exothermic that the hydrogen catches fire; calcium's is less violent and the heat is not enough. (b) Bubbles of hydrogen stick to the surface of calcium and make it float. (c) Magnesium does not react with cold water; it reacts with hot water, and the hydrogen bubbles make it float. $C a (s) + 2 H_{2} O (l) \to C a (O H)_{2} (a q) + H_{2} (g)$
Q6 · 5 marks · Long answerHarder board level
Differentiate between metals and non-metals on the basis of four chemical properties, giving one balanced equation or example for each. (5 marks)
Hint
Think: oxides, dilute acids, type of ions, and reaction with hydrogen.
Answer
1. Oxides: metals give basic oxides ( $2 M g + O_{2} \to 2 M g O$ ; some like $A l_{2} O_{3}$ , ZnO are amphoteric); non-metals give acidic or neutral oxides ( $S + O_{2} \to S O_{2}$ ).
2. Dilute acids: metals above hydrogen displace it ( $M g + 2 H C l \to M g C l_{2} + H_{2}$ ); non-metals do not.
3. Ions: metals lose electrons to form cations ( $N a \to N a^{+} + e^{-}$ ); non-metals gain electrons to form anions ( $C l + e^{-} \to C l^{-}$ ).
4. Non-metals react with hydrogen to form hydrides; metals displace less reactive metals from salt solutions ( $F e + C u S O_{4} \to F e S O_{4} + C u$ ).
(Any four, 1 mark each, plus 1 mark for correct examples.)
Q7 · 3 marks · Short answerHarder board level
(a) Why can sodium not be obtained by heating its oxide with carbon? (b) How is sodium extracted? (c) Write the reactions at the cathode and the anode. (3 marks)
Hint
Who holds oxygen more tightly, sodium or carbon?
Answer
(a) Sodium has more affinity for oxygen than carbon, so carbon cannot reduce its oxide. (b) By electrolytic reduction of molten sodium chloride. (c) Cathode (−): $N a^{+} + e^{-} \to N a$ ; anode (+): $2 C l^{-} \to C l_{2} + 2 e^{-}$ . Sodium is deposited at the cathode and chlorine is liberated at the anode.
Q8 · 3 marks · Short answerBoard level
Name the substance formed on the surface in each case and the substance in air responsible: (a) silver articles turning black, (b) copper losing its shine and turning green, (c) iron in moist air. What two conditions does iron need to rust, as shown by Activity 3.14? (3 marks)
Hint
Look at which tube in Activity 3.14 had rusted nails.
Answer
(a) Silver sulphide; silver reacts with sulphur in the air. (b) Basic copper carbonate; copper reacts with moist carbon dioxide. (c) Rust, a brown flaky substance; iron exposed to moist air. Iron rusts only when both air and water are present (tube A), not with water lacking air (B) or dry air (C).
Q9 · 3 marks · Short answerHOTS / competency
A student wrote: (i) $C u (s) + F e S O_{4} (a q) \to C u S O_{4} (a q) + F e (s)$ ; (ii) 'Aluminium reacts with cold water to form aluminium oxide and hydrogen'; (iii) 'Copper is extracted by electrolysis of its molten chloride because it is very reactive.' Find the error in each and correct it. (3 marks)
Hint
Check each statement against the activity series.
Answer
(i) Copper is less reactive than iron, so no reaction occurs; a correct example is $F e + C u S O_{4} \to F e S O_{4} + C u$ . (ii) Aluminium does not react with cold or hot water; it reacts only with steam: $2 A l + 3 H_{2} O (g) \to A l_{2} O_{3} + 3 H_{2}$ . (iii) Copper is low in reactivity; it is obtained from $C u_{2} S$ just by heating in air. Electrolysis is used for very reactive metals like Na, Mg, Ca.
Q10 · 3 marks · Short answerHOTS / competency
Melting points (K) from your textbook: NaCl 1074, LiCl 887, CaCl2 1045, CaO 2850, MgCl2 981. (a) Which compound has the strongest attraction between its ions? (b) If all five are kept at 1000 K, which would be molten? (c) Which of them would conduct electricity at 1000 K, and why? (3 marks)
Hint
A compound is molten above its melting point.
Answer
(a) CaO, since it has the highest melting point; most energy is needed to break its inter-ionic attraction. (b) LiCl (887 K) and MgCl2 (981 K), as 1000 K is above their melting points. (c) LiCl and MgCl2: in the molten state the ions move freely and carry current; the other three are still rigid solids with ions unable to move.

Test your recall

Answer in your head or on paper first, then open the card. Pulling an answer out of memory makes it stick far better than re-reading.

1.Which metal is a liquid at room temperature, and which non-metal is a liquid?Show answer
Mercury is the liquid metal; bromine is the liquid non-metal.
2.Name two amphoteric oxides.Show answer
Aluminium oxide and zinc oxide.
3.Why are sodium and potassium stored under kerosene?Show answer
They react so vigorously with air that they can catch fire; kerosene keeps air and moisture away.
4.Order of reactivity with dilute HCl seen in Activity 3.11?Show answer
Mg > Al > Zn > Fe; copper does not react.
5.What is gangue?Show answer
Impurities such as soil and sand mixed with a mined ore, which are removed before the metal is extracted.
6.How are sodium, magnesium and calcium extracted?Show answer
By electrolysis of their molten chlorides; the metal deposits at the cathode and chlorine is liberated at the anode.
7.What is anode mud?Show answer
The insoluble impurities that settle below the anode during electrolytic refining.
8.What is solder made of, and why is it used for joining electrical wires?Show answer
Lead and tin; it has a low melting point.

Best order to study it

Learn the physical properties of metals and non-metals, with every exception (mercury, bromine, gallium, caesium, iodine, diamond, graphite, alkali metals).
Work through the reactions with oxygen, water and dilute acids, writing each NCERT equation and balancing it yourself.
Memorise the reactivity series and practise displacement questions, including the Zn, Fe, Cu and Al sulphate practical.
Study ionic bonding: electronic configurations, electron-dot transfer for NaCl, MgCl2, Na2O and MgO, then the four properties of ionic compounds with their reasons.
Learn metallurgy as one flowchart: ore, enrichment, method chosen by reactivity (heat alone, roasting or calcination then carbon, thermit, electrolysis), then electrolytic refining with its diagram.
Finish with corrosion: the three-tube activity, the methods of prevention, galvanising, and alloy examples.

Quick revision checklist

The night before the exam: can you do each of these without looking?

Can you list six physical properties of metals and give one exception to each of four of them?
Can you write and balance the reactions of Na, Ca and Fe with water or steam, with state symbols?
Can you write both reactions of $A l_{2} O_{3}$ that show it is amphoteric?
Can you recite the reactivity series from K to Au without a pause, including hydrogen?
Can you predict whether Zn + FeSO4, Cu + AgNO3 and Ag + CuSO4 react, and write equations for the ones that do?
Can you show electron transfer in MgCl2 and Na2O and name every ion?
Can you give the reason for each property of ionic compounds, including why they conduct when molten but not when solid?
Can you write the roasting, calcination, carbon reduction and thermit equations for zinc and iron?
Can you label the electrolytic refining of copper and say where soluble and insoluble impurities go?
Can you explain tubes A, B and C of the rusting activity and why galvanised iron survives a scratch?

Metals and Non-metals: frequently asked questions

Why is aluminium used for cooking utensils if it is so reactive?

Aluminium quickly forms a thin oxide layer on its surface that protects it from further oxidation. It is also a good conductor of heat with a high melting point. So it heats food well and lasts a long time.

Is Periodic Classification of Elements in the Class 10 board exam?

No. For 2026-27, Periodic Classification of Elements is school-assessed only and is not tested in the board exam.

Do I need to learn every chemical equation in this chapter?

Yes, learn the equations the NCERT text gives: metals with oxygen, water, steam and acids; the amphoteric oxide reactions; roasting, calcination and reduction; thermit; and the electrode reactions. Board answers lose marks for unbalanced equations, so practise balancing each one yourself.

Why does copper not give hydrogen with dilute hydrochloric acid?

Copper is below hydrogen in the reactivity series, so it cannot displace hydrogen from the acid. In Activity 3.11, no bubbles form and the temperature does not change with copper.

What is the difference between a mineral and an ore?

A mineral is any element or compound that occurs naturally in the earth's crust. An ore is a mineral that contains enough of a metal for the metal to be extracted profitably. So every ore is a mineral, but not every mineral is an ore.

Why are alloys used instead of pure metals?

Alloying gives a metal the properties you want. Pure iron is soft, but with a little carbon it becomes hard and strong. With nickel and chromium it becomes stainless steel, which does not rust. Solder has a low melting point, which makes it useful for joining wires.

Based on: CBSE Science (086) syllabus 2026-27; NCERT Science, Textbook for Class X (Reprint 2026-27)