ICSE Class 10 Chemistry Previous Year Question Paper 2017

Question 1

(a) Fill in the blanks from the choices given in brackets:

i. The energy required to remove an electron from a neutral isolated gaseous atom and convert it into a positively charged gaseous ion is called ____________. (electron affinity, ionization potential, electronegativity)

ii. The compound that does not have a lone pair of electrons is __________.

(water, ammonia, carbon tetra chloride)

iii. When a metallic oxide is dissolved in water, the solution formed has a high concentration of ____________ ions (H⁺, h₃O⁺, OH^-)

iv. Potassium sulphite on reacting with hydrochloric acid releases _______ gas. Cl₂, SO₂, H₂S)

v. The compound formed when ethene reacts with Hydrogen is ________.

(CH₄, C₂H₆, C₃H₈)

 

(b) Choose the correct answer from the options given below:

(i) A chloride which forms a precipitate that is soluble in excess of ammonium hydroxide, is:

1. Calcium chloride

2. Ferrous chloride

3. Ferric chloride

4. Copper chloride

 

(ii) If the molecular formula of an organic compound is C₁₀H₁₈ it is:

1. alkene

2. alkane

3. alkyne

4. Not a hydrocarbon

 

(iii) Which of the following is a common characteristic of a covalent compound?

1. high melting point

2. consists of molecules

3. always soluble in water

4. Conducts electricity when it is in the molten state

 

(iv) To increase the pH value of a neutral solution, we should add:

1. an acid

2. an acid salt

3. an alkali

4. a salt

 

(v) Anhydrous iron(III) chloride is prepared by:

1. direct combination

2. simple displacement

3. decomposition

4. neutralization

 

(c) Identify the substance underlined, in each of the following cases:

(i) Cation that does not form a precipitate with ammonium hydroxide but forms one with sodium hydroxide.

(ii) The electrolyte used for electroplating an article with silver.

(iii) The particles present in a liquid such as kerosene, that is a non electrolyte.

(iv) An organic compound containing – COOH functional group.

(v) A solid formed by reaction of two gases, one of which is acidic and the other basic in nature.

 

(d) Write a balanced chemical equation for each of the following:

(i) Action of cold and dilute Nitric acid on Copper.

(ii) Reaction of Ammonia with heated copper oxide.

(iii) Preparation of methane from iodomethane.

(iv) Action of concentrated sulphuric acid on Sulphur.

(v) Laboratory preparation of ammonia from ammonium chloride.

 

(e) State one relevant observation for each of the following reactions:

(i) Addition of ethyl alcohol to acetic acid in the presence of concentrated Sulphuric acid.

(ii) Action of dilute Hydrochloric acid on iron (II) sulphide.

(iii) Action of Sodium hydroxide solution on ferrous sulphate solution.

(iv) Burning of ammonia in air.

(v) Action of concentrated Sulphuric acid on hydrated copper sulphate.

 

(f)

(i) Draw the structural formula for each of the following:

1. 2, 3 – dimethyl butane

2. Diethyl ether

3. Propanoic acid

(ii) Select the process from the following which matches the given description.

(calcination, roasting, pulverisation, smelting)

1. Crushing of the ore into a fine powder.

2. Heating of the ore in the absence of air to a high temperature.

 

(g)

(i) Calculate the number of gram atoms in 4.6 grams of sodium (Na = 23)

(ii) Calculate the percentage of water of crystallization in CuSO₄.5H₂O

(H = 1, O = 16, S = 32, Cu = 64)

(iii) A compound of X and Y has the empirical formula XY₂. Its vapour density is equal to its empirical formula weight. Determine its molecular formula.

 

(h) Match the atomic number 2, 4, 8, 15 and 19 with each of the following:

(i) A solid non metal belonging to the third period.

(ii) A metal of valency 1.

(iii) A gaseous element with valency 2.

(iv) An element belonging to Group 2.

(v) A rare gas.

 

Question 2

(a) Arrange the following as per the instruction given in the brackets:

i. He, Ar, Ne (Increasing order of the number of electron shells)

ii. Na, Li, K (Increasing Ionisation Energy)

iii. F, Cl, Br (Increasing electronegativity)

iv. Na, K, Li (Increasing atomic size)

 

(b) State the type of Bonding in the following molecules:

i. Water

ii. Calcium oxide

 

(c) Answer the following questions:

i. How will you distinguish between Ammonium hydroxide and Sodium hydroxide using copper sulphate solution?

ii. How will you distinguish between dilute hydrochloric acid and dilute sulphuric acid using lead nitrate solution?

 

(d) Identify the salts P and Q from the observations given below:

i. On performing the flame test salt P produces a lilac coloured flame and its solution gives a white precipitate with silver nitrate solution, which is soluble in Ammonium hydroxide solution.

ii. When dilute HCl is added to a salt Q, a brisk effervescence is produced and the gas turns lime water milky.

When NH₄OH solution is added to the above mixture (after adding dilute HCl), it produces a white precipitate which is soluble in excess NH₄OH solution.

 

Question 3

(a) Draw an electron dot diagram to show the formation of each of the following compounds:

i. Methane

ii. Magnesium Chloride

[H = 1, C = 6, Mg = 12, Cl = 17]

 

(b) State the observations at the anode and at the cathode during the electrolysis of:

i. fused lead bromide using graphite electrodes.

ii. copper sulphate solution using copper electrodes.

 

(c) Select the ion in each case, that would get selectively discharged from the aqueous mixture of the ions listed below:

i. SO₄^2-, NO₃^- and OH^-

ii. Pb²⁺, Ag⁺ and Cu²⁺

 

Question 4

(a) Certain blank spaces are left in the following table and these are labelled as A, B, C, D and E. Identify each of them:

 

(b) Write balanced chemical equations to show:

i. The oxidizing action of conc. Sulphuric acid on carbon.

ii. The behavior of H₂SO₄ as an acid when it reacts with Magnesium.

iii. The dehydrating property of conc. Sulphuric acid with sugar.

 

(c) Write balanced chemical equations to show how SO₃ is converted to Sulphuric acid in the contact process.

Question 5

(a)

(i) Propane burns in air according to the following equation:

C₃H₈ + 5O₂ → 3CO₂ + 4H₂O.

What volume of propane is consumed on using 1000 cm³ of air, considering only 20% of air contains oxygen?

(ii) The mass of 11.2 litres of a certain gas at s.t.p. is 24 g. Find the gram molecular mass of the gas.

 

(b) A gas cylinder can hold 1 kg of hydrogen at room temperature and pressure

i. Find the number of moles of hydrogen present.

ii. What weight of CO₂ can the cylinder hold under similar conditions of temperature and pressure? (H = 1, C = 12, O = 16)

iii. If the number of molecules of hydrogen in the cylinder is X, calculate the number of CO₂ molecules in the cylinder under the same conditions of temperature and pressure.

iv. State the law that helped you to arrive at the above result.

 

(c) Write a balanced chemical equation for the preparation of each of the following salts:

i. Copper carbonate

ii. Ammonium sulphate crystals

 

Question 6

(a) Give a balanced chemical equation for each of the following:

i. Action of conc. Nitric acid on Sulphur.

ii. Catalytic oxidation of Ammonia.

iii. Laboratory preparation of Nitric acid.

iv. Reaction of Ammonia with Nitric acid.

 

(b) Identify the term or substance based on the descriptions given below:

i. Ice like crystals formed on cooling an organic acid sufficiently.

ii. Hydrocarbon containing a triple bond used for welding purposes.

iii. The property by virtue of which the compound has the same molecular formula but different structural formulae.

iv. The compound formed where two alkyl groups are linked by  group.

 

(c) Give a balanced chemical equation for each of the following:

i. Preparation of ethane from Sodium propionate

ii. Action of alcoholic KOH on bromethane.

Question 7

(a) Name the following:

i. The process of coating of iron with zinc.

ii. An alloy of lead and tin that is used in electrical circuits.

iii. An ore of zinc containing its sulphide.

iv. A metal oxide that can be reduced by hydrogen.

 

(b) Answer the following questions with respect to the electrolytic process in the extraction of aluminum:

i. Identify the components of the electrolyte other than pure alumina and the role played by each.

ii. Explain why powdered coke is sprinkled over the electrolytic mixture.

 

(c) Complete the following by selecting the correct option from the choices given:

i. The metal which does not react with water or dilute H₂SO₄ but reacts with concentrated H₂SO₄ is _________. (Al/Cu/Zn/Fe)

ii. The metal whose oxide, which is amphoteric, is reduced to metal by carbon reduction ____________. (Fe/Mg/Pb/Al)

iii. The divalent metal whose oxide is reduced to metal by electrolysis of its fused salt is __________. (Al/Na/Mg/K)

Answer 1

(a)

(i) The energy required to remove an electron from a neutral isolated gaseous atom and convert it to a positively charged gaseous ion is called ionisation potential.

(ii) The compound that does not have a lone pair of electrons is carbon tetrachloride.

(iii) When a metal oxide is dissolved in water, the solution formed has a high concentration of OH⁻.

(iv) Potassium sulphite on reacting with hydrochloric acid releases SO₂ gas.

(v) The compound formed when ethane reacts with hydrogen is C₂H₆.

 

(b)

(i) (4) Copper chloride

CuCl₂ + 2NH₄OH → Cu(OH)₂ ↓ + 2NH₄Cl

With excess of NH4OH, the ppt. dissolves.

(ii) (3) alkyne

Alkyne has general molecular formula CnH_2n−2.

(iii) (2) consist of molecules Ionic compound has a high melting point, is always soluble in water and conducts electricity when it is in the molten state. Covalent compounds consist of molecules.

(iv) (3) an alkali Lower range of pH scale (1 to 6) represents acidic nature, while upper

range of pH scale (8 to 14) represents alkaline nature. Therefore, to increase the pH value of a neutral solution (pH = 7), we should add an alkali.

(v) (1) direct combination Anhydrous FeCl₃ cannot be prepared by simply heating hydrated ferric chloride FeCl₃.6H₂O, because on heating, FeCl₃.6H₂O produces Fe₂O₃,

H₂O and HCl.

[FeCl₃ .6H₂O]  Fe₂O₃ + 9H₂O + 6HCl

Direct combination of elements means heating two elements together.

Metal + Nonmetal ⟶ Salt (Soluble / Insoluble)

2Fe + 3Cl₂ ⟶ 2FeCl₃

 

(c)

(i) Cation that does not form a precipitate with ammonium hydroxide but forms one with sodium hydroxide: Ca²⁺

(ii) The electrolyte used for electroplating an article with silver: Sodium argentocyanide or potassium argentocyanide

(iii) The particles present in a liquid such as kerosene that is a nonelectrolyte: Molecules

(iv) An organic compound containing –COOH functional group: Carboxylic acid

(v) A solid formed by a reaction of two gases, one of which is acidic and the other basic in nature: Salt

 

(d)

(i) 3Cu + 8HNO₃ → 3Cu(NO₃)₂ + 4H₂O + 2NO↑

(ii) 3CuO + 3NH₃ → 3Cu + 3H₂O + N₂↑

(iii) CH₃I + 2[H] → CH₄ + HI

(iv) S + 2H₂SO₄ → 3SO₂ + 2H₂O

(v) 2NH₄Cl + Ca(OH)₂ → CaCl₂ + 2H₂O + 2NH₃↑

 

(e)

(i) On addition of ethyl alcohol to acetic acid in the presence of conc.

H₂SO₄ at high temperature, sweet smelling ethyl acetate ester is produced, and the process is known as esterification.

C₂H₅OH + CH₃COOH → CH₃COOC₂H₅ + H₂O

(ii) Dilute hydrochloric acid decomposes iron(II) sulphide to produce iron(II) chloride and hydrogen sulphide having rotten egg smell.

FeS + 2HCl → FeCl₂ + H₂S

(iii) When ferrous sulphate reacts with sodium hydroxide, dirty green gelatinous ppt. of ferrous hydroxide is formed along with colourless sodium sulphate.

FeSO₄ + 2NaOH → Fe(OH)₂↓ + Na₂SO₄

(iv) Since ammonia is not a supporter of combustion, it extinguishes a burning splint and does not burn in air.

(v) Concentrated sulphuric acid removes water of crystallisation from blue-coloured hydrated copper sulphate to form white anhydrous copper sulphate.

  

(f)

(i)

1. 2, 3-dimethyl butane

 

 2. diethyl ether

 

 3. propanoic acid

 

 

(ii)

1. The process of crushing ores into a fine powder in big crushers and ball mills is known as pulverisation.

2. Heating of the ore in the absence of air to a high temperature that is high but insufficient to melt the ore is known as calcination.

 

(g)

(i)

Given:

Mass of sodium = 4.6 g

Atomic mass of Na = 23

Number of gram atom = ?

(ii)

Given :

Atomic mass of H = 1

Atomic mass of O = 16

Atomic mass of S = 32

Atomic mass of Cu = 64

Molar mass of CuSO4.5H₂O = (64) + (32) + (9 × 16) + (10 × 1)

                                                = 250

Molar mass of five water molecules = (10 × 1) + (5 × 16)

                                                             = 90

 

(iii)

Given:

Empirical formula = XY₂

Vapour density = Empirical formula weight

Molecular formula = ?

Molecular weight = n(Empirical formula weight)

       = 2 × V.D.

n(Empirical formula weight) = 2 × V.D.

Since, Vapour density = Empirical formula weight

n = 2

Molecular formula = 2(Empirical formula)

= 2(XY₂)

Molecular formula X₂Y₄

 

(h)

Answer 2

(a)

(i) He < Ne <Ar

(ii) P < Na < Li

(iii) Br < Cl < F

(iv) Li < Na < P

 

(b)

(i) Polar covalent bond

(ii) Ionic bond

 

(c)

(i) Ammonium hydroxide when added to copper sulphate drop-wise forms a pale blue ppt. of copper hydroxide which dissolves in excess of ammonium hydroxide to form a deep blue solution of tetrammine copper sulphate.

Sodium hydroxide when added to copper sulphate drop-wise forms a pale blue ppt. of copper hydroxide which is insoluble in excess of sodium hydroxide solution.

CuSO₄ + 2NaOH ⟶ Cu OH_{2 +} Na₂SO₄

pale blue ppt. colourless

(ii) Sulphuric acid precipitates the insoluble sulphate from lead nitrate solution.

Pb(NO₃)₂ + H₂SO₄ ⟶PbSO₄ + 2HNO₃

Lead nitrate reacts with hydrochloric acid to give a white ppt. of lead chloride.

Pb(NO₃) + 2HCl ⟶ PbCl₂ + 2HNO₃

 

(d)

(i) KCl

(ii) ZnCO₃

 

Answer 3

(a)

(i) Formation of methane molecule:

One atom of carbon shares four electron pairs, one with each of the four atoms of hydrogen.

(ii) Magnesium atom loses 2 electrons to attain a stable electronic configuration and becomes a cation.

Example: 

A non-metallic atom like chlorine gains 1 electron to attain a stable electronic configuration and becomes an anion.

Example: 

Cations and anions are oppositely charged particles which attract one another to form an electrovalent bond leading to the formation of an electrovalent compound.

Here magnesium donates one electron each with two chlorine atoms resulting in the formation of magnesium chloride.

 

(b)

(i) Observations:

Anode: Dark reddish brown fumes of bromine evolve at the anode.

Cathode: Greyish white metal lead is formed on the cathode.

(ii) Observations:

Anode: Nothing gets deposited on the anode because the copper anode dissolves during the reaction as Cu²⁺ ions are formed.

Cathode: Reddish brown Cu is deposited.

 

(c)

(i) OH⁻

(ii) Ag⁺

Answer 4

(a)

(i) A = NaHSO₄ + HCl

B = upward displacement of air

(ii) C = Mg₃N₂ + H₂O

D = Quicklime

E = downward displacement of air

 

(b)

(i) C + 2H₂SO₄ ⟶ CO₂ + 2H₂O + 2SO₂ ↑

(ii) Mg + H₂SO₄ ⟶ MgSO₄ + H₂ ↑

(iii)

 

(c)

SO₃ + H₂SO₄ ⟶ H₂S₂O₇ oleum or pyrosulphuric acid

H₂S₂O₇ + H₂O ⟶ 2H₂SO₄

 

Answer 5

(a)

(i)

Given:

C₃H₈ + 5O₂ → 3CO₂ + 4H₂O

Volume of air = 1000 cm³

Percentage of oxygen in air = 20%

From the given information,

C₃H₈5O₂ ⟶ 3CO₂ + 4H₂O

1vol   5vols   3vols   4vols

According to Gay-Lussac’s law,

1 vol. of propane consumes 5 vol. of oxygen.

Volume of oxygen = 1000 cm³ × 20% = 200 cm³

Therefore,

Volume of propane burnt for every 200 cm³ of oxygen,

40 cm³ of propane is burnt.

(ii) Given:

Volume of gas at STP = 11.2 litres

Mass of gas at STP = 24 g

Gram molecular mass = ?

The mass of 22.4 L of a gas at STP is equal to its gram molecular mass.

11.2 L of the gas at STP weighs 24 g

Therefore,

22.4 L of the gas will weigh

Gram molecular mass = 48 g

 

(b)

Given:

Mass of hydrogen = 1 kg at 298 K and 1 atm pressure

(i) Moles of hydrogen =?

(ii)

At STP, 1 mole of any gas occupies 22.4 L.

So, at STP, 1000 moles of CO₂ will occupy the same space as that of hydrogen.

Atomic masses of C and O are 12 and 16, respectively.

Molar mass of CO₂ = 12 + 32 = 44 g

1000 moles of CO₂ = 44 × 1000 = 44000 g = 44 kg CO₂

Thus, the cylinder can hold 44 kg CO₂.

(iii) 1 mole of any gas = 6.022 × 10²³ molecules 1000 moles of hydrogen = 6.022 × 10²⁶ molecules = X As the number of moles of hydrogen and CO₂ are the same, the number of molecules of CO₂ = X = 6.022 × 10²⁶ molecules of CO₂.

(iv) Avogadro’s law states that under the same conditions of temperature and pressure, equal volumes of different gases have the same number of molecules.

 

(c)

(i) CuO + CO₂ + CuCO₃

(ii) 2NH₃ + H₂SO₄ ⟶ (NH₄)₂SO₄

Answer 6

(a)

  

(b)

(i) Glacial acetic acid

(ii) Acetylene

(iii) Isomerism

(iv) Ketones

 

(c)

 

 

Answer 7

(a)

(i) Electroplating

(ii) Solder

(iii) Zinc blende

(iv) PbO or CuO

 

(b)

(i) Components of electrolyte: Cryolite and fluorspar Role played by each electrolyte is given below:

• Cryolite lowers the fusion temperature from 2050oC to 950oC and enhances conductivity.
• Fluorspar and cryolite act as a solvent for the electrolytic mixture and increase conductivity.

(ii) Powdered coke is sprinkled over the surface of the electrolytic mixture for the following reasons:

• Reduces heat loss by radiation
• Prevents burning of the anode

 

(c)

(i) Cu

(ii) Pb

(iii) Al