This ICSE Class 10 Chemistry Model Paper 2 with Answers is designed for students of Dhingra Classes Nashik. It covers Electrolysis, all four parts of Study of Compounds, and Practical Chemistry, with multiple-choice questions, structured questions, balanced chemical equations, reasoning-based problems, and labelled diagrams.

The four linked Model Papers 1, 3, 4 and 5 have been reviewed for question overlap. This paper uses newly framed questions and different problem scenarios wherever possible. Since the same prescribed chemical principles can appear in different forms, this is an effort to avoid duplicate questions rather than a guarantee that no underlying concept overlaps.

📊 Lessons and marks weightage

The lesson-wise ranges above are indicative study-planning targets, not separate official ICSE allocations. The examination structure below follows the format used in the supplied website references.

General instructions

1. Attempt all questions in Section A.

2. Attempt any four questions from Section B.

3. All questions in this practice paper are followed by their answers for self-study.

4. Write balanced chemical equations wherever required.

5. Draw neat, labelled diagrams and mention observations in practical chemistry questions.

6. Marks allotted to each question or sub-question are shown in brackets.

📕 SECTION A — 40 Marks

Attempt all questions from this section.

Question 1: Multiple-choice questions [15 marks]

Choose the correct option. Each question carries 1 mark.

(i) During electrolysis, which particle moves towards the negative electrode?

(a) Anion (b) Cation (c) Neutron (d) Proton only

Answer: (b) Cation. Positively charged ions move towards the cathode.

(ii) Which change occurs at the cathode during the electrolysis of molten zinc chloride?

(a) Chloride ions lose electrons (b) Zinc ions gain electrons (c) Zinc ions lose electrons (d) Chlorine ions gain protons

Answer: (b) Zinc ions gain electrons.

(iii) In copper electroplating, the metal that supplies copper ions is generally connected to the:

(a) Negative terminal (b) Positive terminal (c) Neutral terminal (d) Switch only

Answer: (b) Positive terminal. The copper anode dissolves to replenish copper ions in the electrolyte.

(iv) Which substance is obtained when hydrogen chloride gas reacts with ammonia gas?

(a) Ammonium nitrate (b) Ammonium sulphate (c) Ammonium chloride (d) Sodium chloride

Answer: (c) Ammonium chloride.

(v) Which of the following best explains why dry hydrogen chloride gas does not change dry blue litmus paper?

(a) It is neutral under all conditions (b) It requires moisture to produce hydrogen ions (c) It contains no hydrogen (d) It reacts with the paper immediately

Answer: (b) It requires moisture to produce hydrogen ions.

(vi) The chemical formula of the salt formed when ammonia reacts completely with sulphuric acid is:

(a) NH₄HSO₄ only (b) (NH₄)₂SO₄ (c) NH₄NO₃ (d) NH₄Cl

Answer: (b)

$(\mathrm{N}{\mathrm{H}}_4{)}_2\mathrm{S}{\mathrm{O}}_4$

(vii) Which gas is mainly responsible for the choking fumes observed when copper reacts with concentrated nitric acid?

(a) Nitrogen dioxide (b) Nitrogen (c) Hydrogen (d) Oxygen

Answer: (a) Nitrogen dioxide,

$\mathrm{N}{\mathrm{O}}_2$

(viii) What is the oxidation state of sulphur in sulphur trioxide,

$\mathrm{S}{\mathrm{O}}_3$

(a) +2 (b) +4 (c) +6 (d) −2

Answer: (c) +6.

(ix) Which property of concentrated sulphuric acid enables it to remove water from certain organic compounds?

(a) Basic nature (b) Dehydrating action (c) Volatility (d) Low density

Answer: (b) Dehydrating action.

(x) Which substance is used to absorb moisture from a gas when it is compatible with that gas?

(a) Any concentrated acid (b) Any alkali (c) A suitable drying agent (d) Distilled water in every case

Answer: (c) A suitable drying agent. Its selection depends on whether it reacts with the gas.

(xi) A solution produces a white precipitate with barium chloride. Which additional observation is most useful for identifying sulphate ions?

(a) The precipitate dissolves readily in dilute hydrochloric acid (b) The precipitate remains insoluble in dilute hydrochloric acid (c) The solution turns red litmus blue (d) A gas burns with a pop

Answer: (b) The precipitate remains insoluble in dilute hydrochloric acid, consistent with barium sulphate.

(xii) Which observation is characteristic of the flame test for sodium ions?

(a) Lilac flame (b) Golden-yellow flame (c) Brick-red flame (d) Apple-green flame

Answer: (b) Golden-yellow flame.

(xiii) What is the main function of a wash bottle containing distilled water in a chemistry laboratory?

(a) To heat substances (b) To rinse precipitates or laboratory apparatus (c) To measure current (d) To collect gases by displacement of air

Answer: (b) To rinse precipitates or laboratory apparatus.

(xiv) A salt solution gives a reddish-brown precipitate on adding aqueous sodium hydroxide. Which ion may be present?

(a) Fe³⁺ (b) Cu²⁺ (c) Zn²⁺ (d) NH₄⁺

Answer: (a) Fe³⁺, due to the formation of reddish-brown iron(III) hydroxide.$$\mathrm{F}{\mathrm{e}}^{3+}+3\mathrm{O}{\mathrm{H}}^{-}\to \mathrm{F}\mathrm{e}(\mathrm{O}\mathrm{H}{)}_3\downarrow$$

(a) Pour water quickly into the acid (b) Heat the acid before mixing (c) Add acid slowly to water with stirring (d) Mix the chemicals in a closed container

Answer: (c) Add acid slowly to water with stirring. The process releases considerable heat.

Question 2: Short-answer questions [12 marks]

(i) Explain why molten lead bromide conducts electricity, whereas solid lead bromide does not. [3]

Answer:

• In molten lead bromide, the ions are free to move and carry electric charge.

• In solid lead bromide, the ions are fixed in their crystal lattice.

• Therefore, molten lead bromide conducts electricity, while solid lead bromide does not conduct through mobile ions.

(ii) Write balanced equations for the following reactions. [3]

(a) Ammonia reacts with oxygen in the absence of a catalyst to form nitrogen and water.

(b) Sulphur dioxide reacts with chlorine in the presence of water to form sulphuric acid and hydrochloric acid.

(c) Sodium sulphite reacts with dilute hydrochloric acid.

Answer:

(a)$$4\mathrm{N}{\mathrm{H}}_3+3{\mathrm{O}}_2\to 2{\mathrm{N}}_2+6{\mathrm{H}}_2\mathrm{O}$$

(b)$$\mathrm{S}{\mathrm{O}}_2+\mathrm{C}{\mathrm{l}}_2+2{\mathrm{H}}_2\mathrm{O}\to {\mathrm{H}}_2\mathrm{S}{\mathrm{O}}_4+2\mathrm{H}\mathrm{C}\mathrm{l}$$

(c)$$\mathrm{N}{\mathrm{a}}_2\mathrm{S}{\mathrm{O}}_3+2\mathrm{H}\mathrm{C}\mathrm{l}\to 2\mathrm{N}\mathrm{a}\mathrm{C}\mathrm{l}+{\mathrm{H}}_2\mathrm{O}+\mathrm{S}{\mathrm{O}}_2\uparrow$$

(iii) Give reasons for the following. [3]

(a) Hydrogen chloride gas is collected by downward displacement of air.

(b) Nitric acid is stored in dark-coloured bottles.

(c) Concentrated sulphuric acid is handled with particular care.

Answer:

(a) Hydrogen chloride is denser than air and is highly soluble in water, so it is collected by downward displacement of air rather than over water.

(b) Nitric acid decomposes in light, producing nitrogen dioxide, which may dissolve in the acid and impart a yellowish colour.

(c) Concentrated sulphuric acid is highly corrosive, and its dilution is strongly exothermic.

(iv) Distinguish between a strong electrolyte and a weak electrolyte, giving one example of each. [3]

Answer:

Question 3: Structured and diagram-based questions [13 marks]

(i) Study the diagram of an electrolytic cell and answer the questions. [4]

(b) State the product formed at the cathode. [1]

(c) Write the half-equation at the anode. [1]

(d) Why must zinc chloride be molten for this process? [1]

Answer:

(a) Zinc ions,

$\mathrm{Z}{\mathrm{n}}^{2+}$

, and chloride ions,

$\mathrm{C}{\mathrm{l}}^{-}$

(b) Zinc metal.

(ii) Answer the following questions on hydrogen chloride. [4]

(a) Name the type of bond present in a hydrogen chloride molecule. [1]

(b) Why does hydrogen chloride show acidic properties in aqueous solution? [1]

(c) Write the balanced equation for its reaction with zinc. [1]

(d) Name the gas evolved in the reaction. [1]

Answer:

(a) Polar covalent bond.

(b) In water, hydrogen chloride ionises to form hydronium ions, which account for its acidic properties.

(iii) A student is given three colourless solutions containing nitrate, sulphate and chloride ions. Describe suitable chemical tests to identify these ions, stating the expected observations. [5]

Answer:

– Chloride ions: Acidify a fresh portion with dilute nitric acid and add silver nitrate solution. A white precipitate of silver chloride forms.

– Nitrate ions: Perform the brown-ring test on a fresh portion by adding freshly prepared iron(II) sulphate solution and carefully layering concentrated sulphuric acid down the side of the test tube. A brown ring at the junction indicates nitrate ions.

Safety: Concentrated sulphuric acid must be handled by a trained person using appropriate protective equipment.

📗 SECTION B — 40 Marks

Attempt any four questions. Each question carries 10 marks. Answers are provided after each question for revision.

Question 4: Electrolysis and electroplating [10 marks]

(i) Explain the electrolysis of aqueous copper(II) sulphate using inert electrodes. Include the products at both electrodes and the relevant electrode equations. [4]

Answer:

• At the cathode, copper(II) ions gain electrons and are deposited as reddish-brown copper.

• At the anode, water or hydroxide ions are oxidised, producing oxygen gas under the usual conditions with inert electrodes.

• The blue colour of the solution gradually becomes less intense as copper(II) ions are removed, although the exact observation depends on the conditions.

Cathode:

Anode:

(ii) Describe the electroplating of a steel spoon with nickel. State the anode, cathode, electrolyte and the purpose of plating. [4]

Answer:

• Anode: Pure nickel plate.

• Cathode: Clean steel spoon.

• Electrolyte: A suitable nickel salt solution, such as nickel sulphate solution.

• Purpose: Nickel plating improves appearance and resistance to corrosion and wear.

During electrolysis, nickel dissolves from the anode:

Answer:

The spoon must be cleaned to remove grease, dirt and oxide layers. A clean surface allows the nickel coating to adhere uniformly and firmly.

Question 5: Ammonia and its chemical properties [10 marks]

(i) Explain why ammonia is collected by downward displacement of air and not over water. [3]

Answer:

• Ammonia is less dense than air.

• It is highly soluble in water and would dissolve substantially if collected over water.

• Therefore, it is collected by downward displacement of air, also called upward delivery.

(ii) Write balanced equations for the following reactions. [3]

(a) Ammonia reacts with hydrogen chloride.

(b) Ammonia reacts with hot copper(II) oxide.

(c) Ammonium chloride reacts with calcium hydroxide on heating.

Answer:

(a)

(b)

(c)

Answer:

1. Manufacture of nitrogenous fertilisers, such as ammonium sulphate.

2. Manufacture of nitric acid and other industrial chemicals.

(iv) Explain why aqueous ammonia turns red litmus paper blue. [2]

Answer:

Ammonia reacts with water to establish an equilibrium that produces hydroxide ions. These ions make the solution alkaline.

(i) Write balanced equations for the reaction of concentrated nitric acid with: [3]

(a) Copper

(b) Carbon

(c) Sulphur

Answer:

(a)

(b)

(ii) Explain the dehydrating action of concentrated sulphuric acid with one suitable example. [3]

Answer:

Concentrated sulphuric acid has a strong affinity for water and can remove hydrogen and oxygen in the proportions present in water from certain compounds.

For example, it dehydrates sucrose, leaving a black mass of carbon.

(iii) State two differences between concentrated sulphuric acid and concentrated nitric acid in their chemical behaviour. [2]

Answer:

1. Concentrated sulphuric acid is a strong dehydrating agent; concentrated nitric acid is chiefly known for its strong oxidising action.

2. Concentrated sulphuric acid can displace hydrogen chloride from a chloride salt because it is a relatively non-volatile acid; nitric acid does not serve the same standard laboratory role in preparing hydrogen chloride.

(iv) Why does concentrated nitric acid generally not liberate hydrogen gas when it reacts with metals? [2]

Answer:

Nitric acid is a strong oxidising agent. It generally oxidises the hydrogen that would otherwise be liberated to water, while nitric acid is reduced to nitrogen oxides or other nitrogen-containing products depending on the reaction conditions.

Question 7: Practical Chemistry and salt analysis [10 marks]

(i) Study the apparatus diagram and answer the questions. [4]

(a) What is the function of the delivery tube? [1]

(b) Why must the apparatus be checked for leaks before collecting a gas? [1]

(c) State one precaution when adding a reagent to a test tube during gas preparation. [1]

(d) Why should a gas not be identified by directly smelling it? [1]

Answer:

(a) It carries the evolved gas from the reaction vessel to the collection or testing apparatus.

(b) Leaks can allow the gas to escape, reduce the yield and expose the experimenter to potentially harmful gases.

(c) Add the reagent carefully, using appropriate protective equipment and avoiding splashing.

(d) Direct inhalation may expose the experimenter to toxic or corrosive gases. Use an approved test or carefully waft only when the procedure specifically permits it.

(ii) A salt solution gives the following observations. Identify the likely ions. [3]

(a) A pale blue precipitate forms on adding aqueous sodium hydroxide. [1]

(b) A white precipitate forms with silver nitrate after suitable acidification with dilute nitric acid. [1]

(c) A dense white precipitate forms with barium chloride and remains insoluble in dilute hydrochloric acid. [1]

Answer:

(a) Copper(II) ions,

$\mathrm{C}{\mathrm{u}}^{2+}$

$\mathrm{C}{\mathrm{l}}^{-}$

$\mathrm{S}{\mathrm{O}}_4^{2-}$

(iii) Why is dilute nitric acid used before adding silver nitrate in the chloride test? [3]

Answer:

Dilute nitric acid acidifies the solution and removes interference from certain anions, particularly carbonate ions, which could otherwise form precipitates with silver ions. Nitric acid is preferred because nitrate ions do not ordinarily interfere with the chloride test.

Question 8: Hydrogen chloride and sulphuric acid [10 marks]

(i) Explain the laboratory preparation of hydrogen chloride gas, giving the reactants, balanced equation and collection method. [4]

Answer:

• Reactants: Solid sodium chloride and concentrated sulphuric acid.

• Method: Concentrated sulphuric acid is added carefully to sodium chloride in a suitable flask, and the mixture is gently heated when required.

• Equation at a lower temperature:

– Collection: Hydrogen chloride gas is collected by downward displacement of air because it is denser than air and highly soluble in water. It must not be collected over water.

(ii) Explain the action of concentrated sulphuric acid on copper on heating. [3]

Answer:

Hot concentrated sulphuric acid acts as an oxidising agent. Copper is oxidised to copper(II) sulphate, while sulphuric acid is reduced to sulphur dioxide.

Observations include the formation of a blue copper(II) sulphate solution and the evolution of colourless, pungent sulphur dioxide gas.

(iii) What is meant by a non-volatile acid? How does this property help in the laboratory preparation of hydrogen chloride? [3]

Answer:

A non-volatile acid has a low tendency to pass into the vapour phase under the relevant conditions.

Concentrated sulphuric acid displaces the more volatile hydrogen chloride from sodium chloride, allowing hydrogen chloride gas to be evolved.

(i) A student passes electric current through a suitable aqueous electrolyte and notices a metallic coating on the cathode. Explain the three essential conditions required to obtain a good electroplated finish. [3]

Answer:

1. The article must be thoroughly cleaned to remove grease, dirt and oxide.

2. The electrolyte must contain suitable ions of the metal to be deposited.

3. Suitable current, voltage and electrolysis time must be maintained to obtain a uniform coating.

(ii) Complete the following reactions and name the principal product asked for. [3]

(a)

$\mathrm{N}{\mathrm{H}}_3+\mathrm{H}\mathrm{N}{\mathrm{O}}_3\to$

(b)

$\mathrm{S}{\mathrm{O}}_3+{\mathrm{H}}_2\mathrm{O}\to$

(c)

$\mathrm{H}\mathrm{C}\mathrm{l}+\mathrm{N}\mathrm{a}\mathrm{O}\mathrm{H}\to$

Answer:

(a)

(b)

Product: Sulphuric acid.

(c)

(iii) A laboratory sample contains an ammonium salt. Describe a test to confirm the presence of ammonium ions and give the ionic equation. [2]

Answer:

Add aqueous sodium hydroxide to the sample and warm it gently. If ammonium ions are present, ammonia gas is evolved. The gas turns moist red litmus paper blue.

Answer:

1. Wear suitable safety goggles, gloves and a laboratory coat; avoid skin and eye contact.

2. When diluting concentrated sulphuric acid, add the acid slowly to water while stirring, never water to concentrated acid.

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