ICSE Class 10 Chemistry Sample Paper 2022 with Solutions

SECTION A

(Attempt all questions.)

Question 1

Choose the correct answers to the questions from the given options. (Do not copy the question, Write the correct answer only.) [10]

(i) The IUPAC name of Ethylene is: [1 Mark]
(a) Propane
(b) Propyne
(c) Ethene
(d) Ethyne

Answer: (c) Ethene

Ethylene is the common name of ethene, which has the formula \( CH_2=CH_2 \).

Teacher's Note:
a) Remember that alkenes end with the suffix -ene and have at least one carbon-carbon double bond.
b) Do not confuse ethene (2 carbons) with propane (3 carbons) or ethyne (triple bond).

(ii) Carbon to carbon double bond is found in: [1 Mark]
(a) 2-butylene
(b) Acetaldehyde
(c) Acetic acid
(d) Ethyl alcohol

Answer: (a) 2-butylene

The suffix -ene indicates the presence of a carbon-carbon double bond in 2-butylene.

Teacher's Note:
a) Functional groups like aldehydes, carboxylic acids, and alcohols contain carbon-oxygen bonds, not necessarily carbon-carbon double bonds.
b) Pay close attention to the IUPAC or common suffixes to identify unsaturation.

(iii) Fused alumina is reduced to aluminium by electrolytic reduction, since: [1 Mark]
(a) Alumina is highly stable
(b) Alumina is least stable
(c) Alumina is not reduced by drying agents.
(d) Alumina is not reduced by reducing agents.

Answer: (a) Alumina is highly stable

Alumina has a high affinity for oxygen and cannot be reduced by common chemical reducing agents.

Teacher's Note:
a) Highly stable metal oxides require electrolytic reduction (Hall Heroult's process) to obtain the pure metal.
b) Ensure you connect metal reactivity with the appropriate method of extraction.

(iv) The catalyst preferred in the conversion of Sulphur dioxide to Sulphur trioxide is: [1 Mark]
(a) Finely divided iron
(b) Graphite
(c) Vanadium pentoxide
(d) platinum

Answer: (c) Vanadium pentoxide

Vanadium pentoxide (\( V_2O_5 \)) is preferred over platinum because it is cheaper and less susceptible to catalytic poisoning.

Teacher'sNote:
a) This is a key step in the industrial Contact process for manufacturing sulphuric acid.
b) Learn the specific catalysts required for important industrial processes such as Haber, Ostwald, and Contact processes.

(v) Substitution reaction is a characteristic property of: [1 Mark]
(a) Alcohols
(b) Alkanes
(c) Alkenes
(d) Alkynes

Answer: (b) Alkanes

Saturated hydrocarbons (alkanes) undergo substitution reactions with halogens in the presence of sunlight.

Teacher's Note:
a) Unsaturated hydrocarbons (alkenes and alkynes) typically undergo addition reactions due to multiple bonds.
b) Be precise about the reaction conditions, such as the need for ultraviolet light or sunlight for alkanes.

(vi) The gas evolved when dilute sulphuric acid reacts with iron sulphide: [1 Mark]
(a) Sulphur dioxide
(b) Carbon dioxide
(c) Hydrogen sulphide
(d) Nitrogen dioxide

Answer: (c) Hydrogen sulphide

Iron sulphide reacts with dilute sulphuric acid to produce ferrous sulphate and hydrogen sulphide gas: \( FeS + H_2SO_4 \rightarrow FeSO_4 + H_2S \uparrow \).

Teacher's Note:
a) Hydrogen sulphide has a characteristic rotten egg smell.
b) Practice writing balanced equations for the action of dilute acids on metal sulphides and carbonates.

(vii) An acid obtained from concentrated nitric acid on reaction with Sulphur: [1 Mark]
(a) Carbonic acid
(b) Sulphuric acid
(c) Nitric acid
(d) Hydrochloric acid

Answer: (b) Sulphuric acid

Concentrated nitric acid oxidises sulphur to form sulphuric acid along with water and nitrogen dioxide.

Teacher's Note:
a) Concentrated nitric acid acts as a strong oxidising agent towards non-metals.
b) Memorise the oxidation products of non-metals like carbon, sulphur, and phosphorus when treated with conc. \( HNO_3 \).

(viii) The hydroxide soluble in excess of ammonium hydroxide is: [1 Mark]
(a) Zinc hydroxide
(b) Lead hydroxide
(c) Magnesium hydroxide
(d) Ferrous hydroxide

Answer: (a) Zinc hydroxide

Zinc hydroxide dissolves in excess ammonium hydroxide to form a soluble complex salt.

Teacher's Note:
a) Know the behaviour of different metallic hydroxides towards excess sodium hydroxide and ammonium hydroxide.
b) Zinc and copper hydroxides show distinctive solubility in excess ammonium hydroxide.

(ix) The chemical name of the principal ore of aluminium: [1 Mark]
(a) Sodium aluminium fluoride
(b) Aluminium oxide
(c) Hydrated Aluminium fluoride
(d) Hydrated aluminium oxide

Answer: (d) Hydrated aluminium oxide

The principal ore of aluminium is bauxite, with the chemical formula \( Al_2O_3 \cdot 2H_2O \), which is hydrated aluminium oxide.

Teacher's Note:
a) Do not confuse the common name (bauxite) with the chemical name (hydrated aluminium oxide) or formula.
b) Learn the common ores, their formulas, and chemical names for all major metals in the syllabus.

(x) A hydrocarbon which is a greenhouse gas. [1 Mark]
(a) Acetylene
(b) Ethylene
(c) Ethane
(d) Methane

Answer: (d) Methane

Methane (\( CH_4 \)) is a primary component of natural gas and acts as a potent greenhouse gas.

Teacher's Note:
a) Greenhouse gases trap outgoing heat radiation from the earth, contributing to global warming.
b) Methane is the simplest alkane and is commonly known as marsh gas.

SECTION B

(Attempt any three questions from this Section.)

Question 2

(i) Define: [2 Marks]
(a) Catenation
(b) Alloy

Answer:
(a) Catenation: The self-linking property of atoms of an element to form very long straight or branched chains and cyclic rings.
(b) Alloy: A homogeneous mixture of two or more metals or a metal with a non-metal.

Teacher's Note:
a) Carbon exhibits catenation to the maximum extent due to its small size and tetravalency.
b) Give relevant examples like duralumin or brass when defining alloys for complete clarity.

(ii) Name the compound formed when: [2 Marks]
(a) Ethene reacts with hydrogen in the presence of a catalyst.
(b) Bauxite reacts with sodium hydroxide

Answer:
(a) Ethane
(b) Sodium meta aluminate

Teacher's Note:
a) The reaction of ethene with hydrogen is catalytic hydrogenation turning an unsaturated compound into a saturated one.
b) Bauxite reacts with NaOH during the leaching step of Baeyer's process to form soluble sodium meta aluminate.

(iii) Draw the structural diagram of: [3 Marks]
(a) Propanal
(b) Ethanoic acid
(c) 1,2 dichloroethane

Answer:
(a) Propanal: \( CH_3-CH_2-CHO \) (showing all single bonds between carbons, double bond between carbon and oxygen of the aldehyde group, and single bonds to hydrogen atoms).
(b) Ethanoic acid: \( CH_3-COOH \) (showing methyl group attached to carbonyl carbon which is bonded to a hydroxyl group -OH and double-bonded to oxygen).
(c) 1,2-dichloroethane: \( ClCH_2-CH_2Cl \) (two carbon atoms single-bonded to each other, each bonded to two hydrogens and one chlorine atom).

Teacher's Note:
a) Ensure all tetravalency requirements of carbon and valency of other atoms are correctly shown with bonds.
b) Clearly represent functional groups like aldehyde (-CHO), carboxylic acid (-COOH), and halogen substituents.

(iv) Complete and balance the following chemical equations: [3 Marks]
(a) \( C_2H_6 + O_2 \rightarrow \)
(b) \( C_2H_2 + I_2 \rightarrow \)
(c) \( NH_3 + HCl \rightarrow \)

Answer:
(a) \( 2C_2H_6 + 7O_2 \rightarrow 4CO_2 + 6H_2O \)
(b) \( C_2H_2 + I_2 \rightarrow C_2H_4I_2 \)
(c) \( NH_3 + HCl \rightarrow NH_4Cl \)

Teacher's Note:
a) Complete combustion of alkanes yields carbon dioxide and water vapour.
b) Addition of halogens to alkynes or alkenes yields dihalo or tetrahalo addition products.

Question 3

(i) Identify the anion present in the following compounds. [2 Marks]
(a) Compound Z which on reacting with dilute sulphuric acid liberates a gas which has no effect on acidified potassium dichromate but turns lime water milky.
(b) The solution of Compound L on reacting with freshly prepared ferrous sulphate solution followed by addition of few drops of concentrated sulphuric acid to the reactants along the sides of a test tube forms a brown ring at the junction of the two liquids.

Answer:
(a) Carbonate ion (\( CO_3^{2-} \)) (or bicarbonate ion, \( HCO_3^- \))
(b) Nitrate ion (\( NO_3^- \))

Teacher's Note:
a) Carbon dioxide turns lime water milky due to the formation of insoluble calcium carbonate.
b) The brown ring test is a confirmatory ring test specifically used for identifying nitrate radicals.

(ii) State the following: [2 Marks]
(a) The drying agent used in the laboratory preparation of HCl gas.
(b) Products formed when ammonia is burnt in excess of oxygen.

Answer:
(a) Concentrated sulphuric acid (\( conc. \, H_2SO_4 \))
(b) Nitrogen gas and water vapour

Teacher's Note:
a) Concentrated sulphuric acid is chosen because it is non-volatile and does not react with hydrogen chloride gas.
b) Note that ammonia burns in oxygen with a yellowish-green flame to produce nitrogen and water, unlike catalytic oxidation which gives nitric oxide.

(iii) State the observation for the following, when: [3 Marks]
(a) Manganese dioxide reacts with concentrated HCl.
(b) A glass rod dipped in concentrated HCl acid is brought near ammonia gas.
(c) Concentrated sulphuric acid is added to carbon.

Answer:
(a) A greenish-yellow gas (chlorine) is evolved which turns moist starch-iodide paper blue-black.
(b) Dense white fumes of ammonium chloride are formed.
(c) A colourless gas mixture of carbon dioxide and sulphur dioxide is evolved as carbon gets oxidised.

Teacher's Note:
a) Concentrated HCl acts as a reducing agent when reacted with strong oxidising agents like manganese dioxide.
b) The formation of dense white fumes is a classic confirmatory test for both ammonia and hydrogen chloride gases.

(iv) Write balanced equation for the following conversions: [3 Marks]
(a) Lead sulphate from lead nitrate and sulphuric acid.
(b) Nitrogen tri chloride from ammonia.
(c) Sodium chloride from sodium sulphite and dilute hydrochloric acid.

Answer:
(a) \( Pb(NO_3)_2 + H_2SO_4 \rightarrow PbSO_4 \downarrow + 2HNO_3 \)
(b) \( NH_3 + 3Cl_2 \rightarrow NCl_3 + 3HCl \)
(c) \( Na_2SO_3 + 2HCl \rightarrow 2NaCl + H_2O + SO_2 \uparrow \)

Teacher's Note:
a) Lead sulphate is insoluble and precipitates out as a white solid.
b) Excess chlorine reacts with ammonia to form explosive nitrogen trichloride.

Question 4

(i) State the relevant reason for the following: [2 Marks]
(a) A layer of powdered coke is used over the electrolytic mixture in Hall Heroult's process.
(b) Graphite anodes are continuously replaced during the electrolysis of alumina.

Answer:
(a) Powdered coke prevents heat loss by radiation and stops the burning of the carbon anode in air.
(b) The oxygen liberated at the anode reacts with the graphite anode to form carbon monoxide and carbon dioxide, causing it to burn away gradually.

Teacher's Note:
a) Both points highlight practical aspects of the extraction of aluminium via Hall Heroult's process.
b) Clearly mention the formation of carbon gases at the anode for part (b).

(ii) Name the alloys for the given composition: [2 Marks]
(a) Magnesium and aluminium
(b) Magnesium + Manganese + Aluminium + Copper

Answer:
(a) Magnalium
(b) Duralumin

Teacher's Note:
a) Magnalium is light and strong, making it useful for structural components and optical instruments.
b) Duralumin contains a major proportion of aluminium along with copper, magnesium, and manganese.

(iii) Identify the terms for the following: [3 Marks]
(a) The experiment which demonstrates high solubility of ammonia gas.
(b) A method used to collect HCl gas.
(c) The electrode where reduction takes place.

Answer:
(a) Fountain experiment
(b) Upward displacement of air (downward delivery)
(c) Cathode

Teacher's Note:
a) The fountain experiment strikingly proves the extreme solubility of ammonia gas in water.
b) HCl gas is heavier than air, hence it is collected by downward delivery.

(iv) Complete the table given below: [3 Marks]

Answer:
(a) Fixation of atmospheric nitrogen (or Ostwald's process final absorption step)
(b) Nitric acid (\( HNO_3 \))
(c) Contact process (dilution of oleum)

Teacher's Note:
a) Ensure all blanks are filled with precise scientific terms and chemical formulas.
b) The dissolution of oleum in water is the final step for manufacturing commercial sulphuric acid.

Question 5

(i) Write the balanced chemical equation to show the concentration of ore in Baeyer's process. [2 Marks]
(a) Sodium aluminate to aluminium hydroxide
(b) Aluminium hydroxide to alumina

Answer:
(a) \( NaAlO_2 + 2H_2O \rightarrow NaOH + Al(OH)_3 \downarrow \)
(b) \( 2Al(OH)_3 \xrightarrow{1000^{\circ}C} Al_2O_3 + 3H_2O \)

Teacher's Note:
a) Hydrolysis of sodium aluminate is seeded with freshly precipitated aluminium hydroxide at a warm temperature.
b) Ignition of aluminium hydroxide drives off water to yield pure alumina.

(ii) Select the correct answer from the brackets to complete the following statements: [2 Marks]
(a) The catalyst used in the oxidation of ammonia is __________ [zinc / platinum].
(b) The product formed when ammonia reacts with oxygen is _________ [nitric oxide / nitrous oxide]

Answer:
(a) platinum
(b) nitric oxide

Teacher's Note:
a) Platinum gauze acts as a catalyst at around \( 800^{\circ}C \) in the catalytic oxidation of ammonia.
b) The product is nitric oxide (\( NO \)), which further reacts with oxygen to form brown nitrogen dioxide.

(iii) Name the following organic compound: [3 Marks]
(a) The compound with 3 carbon atoms whose functional group is a carboxylic acid.
(b) The first homologue whose general formula is \( C_nH_{2n} \).
(c) The compound formed by complete chlorination of ethyne.

Answer:
(a) Propanoic acid
(b) Ethene
(c) 1,1,2,2-Tetrachloroethane

Teacher's Note:
a) Carboxylic acids have the -COOH suffix designated as 'oic acid'.
b) Alkenes require a minimum of two carbon atoms, making ethene the first member of the \( C_nH_{2n} \) series.

(iv) Answer the following questions related to the laboratory preparation of the hydrogen chloride gas: [3 Marks]
(a) Why is sodium chloride preferred to other metallic chlorides?
(b) State the temperature required in the preparation.
(c) Write the chemical equation.

Answer:
(a) Sodium chloride is cheap and readily available.
(b) Below \( 200^{\circ}C \) (nearly \( 200^{\circ}C \)).
(c) \( NaCl + H_2SO_4 \xrightarrow{\lt 200^{\circ}C} NaHSO_4 + HCl \uparrow \)

Teacher's Note:
a) Sodium chloride is an economical raw material compared to other metal chlorides.
b) Keeping the temperature below \( 200^{\circ}C \) prevents damage to glass apparatus and saves fuel.

Question 6

(i) Distinguish between the following: [2 Marks]
(a) Dilute HCl and dilute \( HNO_3 \) [using silver nitrate solution]
(b) Dilute HCl and dilute \( H_2SO_4 \) [using lead nitrate solution]

Answer:
(a) Dilute HCl reacts with silver nitrate to give a curdy white precipitate of silver chloride, whereas dilute \( HNO_3 \) does not react.
(b) Both give white precipitates with lead nitrate, but lead chloride dissolves on heating in hot water while lead sulphate remains insoluble.

Teacher's Note:
a) Silver chloride is soluble in ammonium hydroxide but insoluble in dilute nitric acid.
b) Solubility differences in hot water are classic laboratory tests for distinguishing chloride and sulphate ions.

(ii) Give one word for the following statements: [2 Marks]
(a) Naturally occurring minerals from which metals are extracted.
(b) Organic compounds having the same molecular formula but different Structural formula.

Answer:
(a) Ores
(b) Isomers

Teacher's Note:
a) All ores are minerals, but not all minerals are ores (metals cannot be profitably extracted from all minerals).

b) Isomerism gives rise to distinct physical and chemical properties among compounds with identical molecular formulas.

(iii) A, B and C are the chemical properties of sulphuric acid: [3 Marks]
A. Oxidizing agent
B. Dehydrating agent
C. Non volatile acid
Match the following equations 1 to 3 to the above chemical properties of sulphuric acid.
1. \( KNO_3 + H_2SO_4 \rightarrow KHSO_4 + HNO_3 \)
2. \( C_{12}H_{22}O_{11} \rightarrow 12C + 11H_2O \)
3. \( S + 2H_2SO_4 \rightarrow 2H_2O + 3SO_2 \)

Answer:
A matches 3 (\( S + 2H_2SO_4 \rightarrow 2H_2O + 3SO_2 \))
B matches 2 (\( C_{12}H_{22}O_{11} \rightarrow 12C + 11H_2O \))
C matches 1 (\( KNO_3 + H_2SO_4 \rightarrow KHSO_4 + HNO_3 \))

Teacher's Note:
a) Sulphuric acid's high boiling point makes it non-volatile, enabling the preparation of more volatile acids like nitric acid.
b) Its strong affinity for water allows it to act as a dehydrating agent towards organic compounds like sugar and starch.

(iv) Study and complete the following table: [3 Marks]

Answer:
1. \( C_nH_{2n-2} \)
2. Methane (for the first member of the alkane series)
3. Acetylene

Teacher's Note:
a) Know the general formulas for alkanes (\( C_n H_{2n+2} \)), alkenes (\( C_n H_{2n} \)), and alkynes (\( C_n H_{2n-2} \)).
b) Methane is commonly referred to as marsh gas, while ethyne is widely known by its common name acetylene.