Solved 2024 Question Paper ICSE Class 10 Chemistry

Unsaturated hydrocarbons undergo:

1. Addition reaction
2. Substitution reaction
3. Oxidation reaction
4. Redox reaction

Answer

Addition reaction

Reason — The availability of electrons in the double or triple bonded unsaturated hydrocarbons makes them more reactive and they therefore undergo characteristic addition reactions only.

In the 2nd period Neon has maximum Ionization Potential because:

1. It has unstable electronic configuration.
2. It easily accepts electrons.
3. It easily loses electrons.
4. The outer most shell is completely filled.

Answer

The outer most shell is completely filled.

Reason — The outer most shell is completely filled making it extremely stable and requiring more energy to remove an electron. Therefore, Neon has maximum Ionization Potential in the 2nd period.

Copper, Zinc and Tin are the metals alloyed to form:

1. Duralumin
2. Brass
3. Bronze
4. Solder

Answer

Bronze

Reason — Bronze is an alloy of 80% copper, 2% Zinc and 18% Tin.

The metal hydroxide which reacts with both acids and alkalis to form salt and water is:

1. Calcium hydroxide
2. Magnesium hydroxide
3. Aluminium hydroxide
4. Ferric hydroxide

Answer

Aluminium hydroxide

Reason — As Al(OH)₃ is amphoteric in nature, it can generate salt and water as well as behave as a base with a strong acid.

Reaction of an alcohol with a carboxylic acid in the presence of concentrated H₂SO₄ is termed as:

1. Halogenation
2. Esterification
3. Hydrogenation
4. Dehydrohalogenation

Answer

Esterification

Reason — The reaction of an alcohol with a Carboxylic acid in the presence of conc. H₂SO₄ forms an ester. This is called an esterification reaction.

Conversion of Ethanol to Ethene by the action of concentrated sulphuric acid involves:

1. Dehydration
2. Dehydrogenation
3. Dehydrohalogenation
4. Hydrolysis

Answer

Dehydration

Reason — Dehydration involves elimination of elements of water from alcohol. Conc. sulphuric acid act as dehydrating agent.

$\underset{\text{ ethyl alcohol}}{\text{C}_2\text{H}_5\text{OH}} \xrightarrow[170\degree\text{C}]{\text{Conc. H}_2\text{SO}_4\text{[excess]}} \underset{ \text{ethene}}{\text{C}_2\text{H}_4} + \text{H}_2\text{O}\$

The products formed are ethene and water.

The oxidizing agent in the equation S + 2H₂SO₄ ⟶ 3SO₂ + 2H₂O is:

1. Sulphur
2. Sulphuric acid
3. Sulphur dioxide
4. Water

Answer

Sulphuric acid

Reason — Sulphuric acid donates oxygen atoms to sulphur, leading to the formation of SO₂ and water (H₂O). Thus, sulphuric acid acts as an oxidizing agent.

Electron Affinity is maximum in:

1. Mg
2. Ar
3. Li
4. Br

Answer

Br

Reason — Electron affinity tends to be highest for elements on the right side of the periodic table. Therefore, Bromine (Br) is likely to have the highest electron affinity.

The compound that is not a constituent of the electrolytic mixture used in the Hall-Heroult's process is:

1. Al₂O₃
2. NaAlO₂
3. Na₃AlF₆
4. CaF₂

Answer

CaF₂

Reason — Calcium fluoride is not part of the standard Hall-Heroult electrolytic mixture.

On passing ammonia gas over heated copper oxide for some time, a reddish-brown residue is left behind. What property of ammonia is demonstrated here?

1. Basic property
2. Oxidising property
3. Reducing property
4. Acidic property

Answer

Reducing property

Reason — Ammonia reduces Black Copper [II] oxide to reddish brown copper as shown in the below equation:

2NH₃ + 3CuO ⟶ 3Cu + 3H₂O + N₂↑

Rotten egg smell is due to the liberation of:

1. HCl gas
2. H₂S gas
3. Cl₂ gas
4. SO₂ gas

Answer

H₂S gas

Reason — The rotten egg smell is commonly associated with Hydrogen sulphide (H₂S) gas. H₂S is a colourless gas and is known for its strong, unpleasant odour, similar to that of rotten eggs.

Ammonia gas is collected by downward displacement of air since ammonia is:

1. very slightly soluble in water.
2. heavier than air.
3. lighter than air.
4. insoluble in water.

Answer

lighter than air

Reason — Ammonia gas is lighter than air and hence collected by the downward displacement of air. Ammonia is not collected over water since it is highly soluble in water.

Which of the following would occupy 22.4 litres at S.T.P.?

(1) 32g of oxygen gas

(2) 2 moles of hydrogen gas

(3) 6.022 x 10²³ molecules of ammonia

1. 1 & 2
2. 1 & 3
3. 2 & 3
4. 1, 2 & 3
   [Atomic weights: O = 16, H = 1, N = 14]

Answer

1 & 3

Reason — (1) The molar mass of O₂ = 2 × atomic mass of oxygen ≈ 32 g/mol.
So, 32 grams of O₂ is equivalent to 1 mole of O₂. 1 mole of any gas at S.T.P. occupies 22.4 liters.

(2) 2 moles of hydrogen gas will occupy 2 x 22.4 = 44.8 litres

(3) 1 mole of NH₃ contains 6.022 × 10²³ molecules and occupies 22.4 liters at S.T.P. Therefore, 6.022 × 10²³ molecules of NH₃ will also occupy 22.4 liters at S.T.P.

In the molecule of water, oxygen atom has:

1. One shared pair of electrons.
2. Three shared pairs of electrons.
3. Two lone pairs of electrons.
4. One lone pair of electrons

Answer

Two lone pairs of electrons

Reason — Water contains two hydrogen atoms and one oxygen atom. The hydrogen atom [1] has one electron in it's valence shell while the oxygen atom [2, 6] has 6 electrons in it's valence shell. Two hydrogen atom share one electron each and two unshared pairs of electrons are left as lone pairs as shown in the diagram below :

A mineral from which the metal can be extracted economically and conveniently is known as:

1. Matrix
2. Ore
3. Flux
4. Alloy

Answer

Ore

Reason — Ore is the mineral that contains a high enough concentration of the desired metal. Ores can be economically and conveniently processed to obtain the metal.

The following sketch represents the electroplating of an Iron cup with Nickel metal. Study the diagram and answer the following questions:

(a) During electroplating the iron cup is placed at the cathode. Why?

(b) Name the ion that must be present in the electrolyte.

(c) State one condition that is necessary to ensure that the deposit is smooth, firm and even.

(d) Write the reaction taking place at the cathode.

(e) What change would you observe at the anode?

Answer

(a) In electroplating, the cathode is the electrode where reduction (gain of electrons) occurs. The iron cup is placed at the cathode because the metal ions from the electrolyte will be reduced and deposit onto the iron cup. This process coats the iron cup with a layer of metal, achieving the plating effect.

(b) Ni²⁺ must be present in the electrolyte.

(c) A low current for a longer time should be used as longer time and low current initiates a thicker, uniform deposit.

(d) Ni²⁺ + 2e^- → Ni

(e) The Nickel plate is gradually dissolved as ions in solution.

Match the Column A with Column B:

Answer

Complete the following sentences by choosing the correct answer from the brackets:

(a) The salt that can be prepared by Direct Combination is ............... . [FeCl₃ / FeCl₂]

(b) The metallic oxide which can be reduced by using common reducing agents is ............... . [Fe₂O₃ / Al₂O₃]

(c) The metal nitrate which on thermal decomposition forms a black residue is ............... . [zinc nitrate / copper nitrate]

(d) During the electrolysis of copper sulphate solution, if ............... is used as electrodes, the colour of the electrolyte does not fade. [copper / platinum]

(e) The process of heating the concentrated ore in a limited supply or absence of air is ............... . [roasting / calcination]

Answer

(a) The salt that can be prepared by Direct Combination is FeCl₃ .

(b) The metallic oxide which can be reduced by using common reducing agents is Fe₂O₃ .

(c) The metal nitrate which on thermal decomposition forms a black residue is copper nitrate .

(d) During the electrolysis of copper sulphate solution, if copper is used as electrodes, the colour of the electrolyte does not fade.

(e) The process of heating the concentrated ore in a limited supply or absence of air is calcination .

State the terms for the following:

(a) The group obtained by removing one hydrogen atom from the parent alkane.

(b) Two metal plates or wires through which the current enters and leaves the electrolytic cell.

(c) The amount of substance which contains the same number of units as the number of atoms in carbon-12.

(d) The tendency of an atom to pull a shared pair of electrons towards itself in a compound.

(e) The formula which represents the simplest ratio between the atoms of elements present in a compound.

Answer

(a) Alkyl group

(b) Electrodes

(c) Mole

(d) Electronegativity

(e) Empirical formula

(a) Give the IUPAC names of the organic compounds represented by the structural formulae given below:

(b) Draw the structural diagram for the following organic compounds:

1. 3-methyl pentane
2. propyne
3. methanal

Answer

(a) IUPAC names are:

1. 2,3-Dichloropentane
2. 1-Propanoic acid

(b) Structural formula

1. 3-methyl pentane

2. Propyne

3. Methanal

Rewrite the following statements by adding the correct word as shown in the example:

Example:

Given Statement: Ammonia changes moist red litmus to blue.

Correct Statement: Aqueous ammonia changes moist red litmus to blue.

(a) Sulphuric acid acts as a dehydrating agent.

(b) Ammonia reacts with chlorine to give ammonium chloride and nitrogen.

Answer

(a) Concentrated sulphuric acid acts as a dehydrating agent.

(b) Excess of ammonia reacts with chlorine to give ammonium chloride and nitrogen.

Identify only the anion present in the following compound:

(a) The compound on heating produces a colourless, odourless gas which turns lime water milky and has no effect on acidified potassium dichromate solution.

(b) The solution of the compound which on treating with concentrated sulphuric acid and freshly prepared ferrous sulphate solution produces a brown ring.

Answer

(a) The gas that turns lime water milky is carbon dioxide. Since the gas produced is CO₂, the anion in the compound is carbonate (CO₃^2-).

(b) The brown ring test indicates the presence of nitrate ions (NO₃^-).

Mohan has three solutions P, Q and R having a pH of 13, 5 and 2 respectively. Which of the above solutions P, Q or R:

(a) will react with Magnesium to liberate hydrogen gas?

(b) will liberate ammonia gas when it reacts with ammonium chloride?

(c) will contain molecules as well as ions?

Answer

(a) Magnesium reacts with acids to liberate hydrogen gas. Therefore, Solutions Q (pH 5) and R (pH 2) will react with magnesium to liberate hydrogen gas.

(b) Ammonium chloride reacts with strong bases to release ammonia gas. A solution with a high pH (basic nature) is required for this reaction to take place. Solution P, with a pH of 13, is strongly basic and will liberate ammonia gas when it reacts with ammonium chloride.

(c) Solution Q (pH 5) will contain both molecules (of the weak acid) and ions (hydrogen ions), as it is a moderately acidic solution where some acid will be in molecular form and some in ionic form.

The following table is related to an Industrial process of an acid.

Identify (a), (b) and (c).

Answer

(a) → Contact Process

(b) → Vanadium pentoxide

(c) → Sulphur trioxide (SO₃)

Define the following terms:

(a) Molar volume

(b) Normal salt

Answer

(a) Molar volume — The molar volume of a gas is the volume occupied by one gram-molecular mass or by one mole of the gas at S.T.P. It is equal to 22.4 dm³.

(b) Normal salt — Normal salt is formed by complete replacement of the replaceable hydrogen ion of an acid molecule by a basic radical [metallic or ammonium ion].

Draw the electron dot structure of:

(a) Methane molecule

(b) Nitrogen molecule

[Atomic number: N = 7, C = 6, H = 1]

Answer

(a) Electron dot structure of Methane molecule is shown below:

(b) Electron dot structure of Nitrogen molecule is shown below:

Complete and balance the following equations:

(a) Al₂O₃ + 2NaOH ⟶

(b) C₂H₅COONa + NaOH $\overset{\text{Δ}}{\underset{\text{Cao}}{\longrightarrow}}$

(c) C₂H₄Br₂ + alcoholic KOH $\overset{\text{Δ}}{\longrightarrow}$

Answer

(a) Al₂O₃ + 2NaOH ⟶ 2NaAlO₂ + H₂O

(b) C₂H₅COONa + NaOH $\overset{\text{Δ}}{\underset{\text{Cao}}{\longrightarrow}}$ C₂H₆ + Na₂CO₃

(c) C₂H₄Br₂ + 2KOH (alcoholic) $\overset{\text{Δ}}{\longrightarrow}$ C₂H₂ + 2KBr + 2H₂O

Choose the organic compound from the list given below to answer the following questions:

$\boxed{\text{Ethene, Ethanoic acid, Ethanol, Methanal}}$

(a) The compound which does not have a double bond in its structure.

(b) The compound which in its pure form turns into an ice like solid on cooling.

(c) The compound which is used for artificial ripening of fruits.

Answer

(a) Ethanol

(b) Ethanoic acid

(c) Ethene

Name the main metal used in making of the alloys given below:

(a) Duralumin

(b) Stainless steel

Answer

(a) Aluminium

(b) Iron

Differentiate between the following pairs based on the criteria given:

(a) Sulphuric acid and Nitric acid (using barium chloride solution)

(b) Unsaturated and Saturated hydrocarbons (type of bond present)

Answer

(a) When sulphuric acid is added to a solution of barium chloride it reacts with barium chloride to form barium sulphate which is a white precipitate.

H₂SO₄ + BaCl₂ ⟶ BaSO₄↓ + 2HCl

When nitric acid is added to barium chloride, there is no reaction to form a precipitate because nitric acid does not contain sulphate ions. The solution remains clear.

(b) Unsaturated Hydrocarbons contain one or more double or triple bonds between carbon atoms. Examples include alkenes (with double bonds) and alkynes (with triple bonds). Saturated Hydrocarbons only have single bonds between carbon atoms.

Calcium carbonate reacts with dilute hydrochloric acid as given below:

CaCO₃ + 2HCl ⟶ CaCl₂ + H₂O + CO₂

(a) What is the mass of 5 moles of calcium carbonate? (Relative molecular mass of calcium carbonate is 100)

(b) How many moles of HCl will react with 5 moles of calcium carbonate?

(c) What is the volume of carbon dioxide liberated at S.T.P. at the same time?

Answer

(a) Given,

1 mole of CaCO₃ = molecular mass of CaCO₃ = 100 g

∴ 5 moles of CaCO₃ weighs = 100 x 5 = 500 g

(b) 1 mole of CaCO₃ requires 2 moles of HCl.

∴ 5 moles of CaCO₃ will require 2 x 5 = 10 moles of HCl

(c) 1 mole of CaCO₃ produces 1 mole of CO₂ and 1 mole occupies 22.4 l of volume.

∴ 5 moles of CaCO₃ will produce 5 moles of CO₂ and 5 moles will occupy 22.4 x 5 = 112 L

Identify the gas evolved in each of the following reactions:

(a) Methane undergoes complete combustion.

(b) Copper carbonate is heated.

(c) MnO₂ reacts with concentrated HCl.

Answer

(a) Carbon dioxide
CH₄ + 2O₂ ⟶ CO₂ + 2H₂O

(b) Carbon dioxide
CuCO₃ ⟶ CuO + CO₂

(c) Chlorine
MnO₂ + 4HCl ⟶ MnCl₂ + 2H₂O + Cl₂

X - HCl ⇋ H¹⁺ + Cl^- (in solution state)

Y - PbBr₂ ⇋ Pb²⁺ + 2Br^1- (in molten state)

From the above reactions X or Y, identify the reaction which exhibits:

(a) electrolytic dissociation

(b) ionization

Answer

(a) Y is electrolytic dissociation.

Reason — PbBr₂ is an electrovalent compound and its contains lead [Pb²⁺] and bromide [Br^1-] ions that are held together by an electrostatic force of attraction. Melting causes the separation of these ions. Hence, it exhibits electrolytic dissociation.

(b) X is ionization.

Reason — HCl is a polar covalent compound. In gaseous state or pure liquid state, it does not conduct an electric current. When HCl is added to water, formation of Hydronium [(H₃O)⁺] and Chloride [Cl^-] ions takes place. Hence, it exhibits ionization.

Give reasons for the following:

(a) Inert gases do not form ions.

(b) Covalent compounds have a low melting and boiling point.

Answer

(a) Inert gases have completely filled octet which makes them extremely stable. They neither lose, nor gain electrons. Hence, they do not form ions.

(b) Covalent compounds have low melting and boiling points because they have weak forces of attraction between the binding molecules, thus less energy is required to break the force of bonding.

Arrange the following as per the instructions given in the brackets:

(a) Carbon, Fluorine, Beryllium (decreasing order of atomic size)

(b) Sulphuric acid, Phosphoric acid, Acetic acid (increasing order of number of replaceable H atoms per molecule)

(c) Potassium, Lithium, Sodium (increasing order of ionization potential)

Answer

(a) Beryllium > Carbon > Fluorine

(b) Acetic acid < Sulphuric acid < Phosphoric acid

(c) Potassium < Sodium < Lithium

Identify the following:

(a) An element in period 1 which can be placed in both group 1 and group 17 of the Periodic Table.

(b) The element having electronic configuration 2, 8, 6.

(c) The most electronegative element of period 3.

Answer

(a) Hydrogen

(b) Sulphur

(c) Chlorine

Rita was given an unknown salt for identification. She prepared a solution of the salt and divided it into two parts.

• To the first part of the salt solution, she added a few drops of ammonium hydroxide and obtained a reddish-brown precipitate.
• To the second part of the salt solution, she added a few drops of silver nitrate solution and obtained a white precipitate.

Name:

(a) the cation present and

(b) the anion present in the salt given for identification.

Answer

(a) The cation present is Ferric (Fe³⁺).

Reason — A reddish-brown precipitate with ammonium hydroxide indicates the presence of Ferric ions. When ammonium hydroxide is added to a solution containing Fe³⁺ ions, a reddish-brown precipitate of Ferric hydroxide forms.

(b) The anion present is Chloride (Cl^-).

Reason — A white precipitate with silver nitrate suggests the presence of Chloride ions (Cl^-). Silver nitrate reacts with chloride ions to form a white precipitate of silver chloride (AgCl).

Fill in the blanks by choosing the correct answer from the bracket

(a) Carbon tetrachloride is a ............... [polar / non-polar] covalent molecule.

(b) During electrolysis of acidulated water, the gas liberated at the anode is ............... [oxygen / hydrogen].

Answer

(a) Carbon tetrachloride is a non-polar covalent molecule.

(b) During electrolysis of acidulated water, the gas liberated at the anode is oxygen .

Ammonia burns in oxygen as shown below.

4NH₃ + 3O₂ ⟶ 2N₂ + 6H₂O

If 240 cc of ammonia is burnt in 300 cc of oxygen, find out the composition of the resultant gaseous mixture at room temperature.

Answer

According to the given equation:

For N₂

4 vol. of NH₃ produce 2 vol. of N₂

∴ 240 cc of NH₃ will produce = $\dfrac{2 \times 240}{4}$ = 120 cc of N₂

For O₂

4 vol. of NH₃ reacts with 3 vol. of O₂

∴ 240 cc of NH₃ will react with = $\dfrac{3 \times 240}{4}$ = 180 cc of O₂.

Amount of unused Oxygen = 300 cc - 180 cc = 120 cc

Hence, composition of the resultant gaseous mixture at room temperature is 120 cc of O₂ + 120 cc of N₂

The following table shows the electronic configuration of the atoms A, B, C and D.

(a) Write the formula of the compound formed between:

1. A and B
2. D and C

(b) Which of the above elements will exhibit catenation?

Answer

(a)

1. AB is the formula of the compound formed between A and B.
   Reason — A has 2 electrons in its outermost shell. B has 6 electrons in its outermost shell. To form a compound between A and B, A will donate its 2 outermost electrons to B. Hence, the formula of the compound is AB as both have 2 as valency.

2. DC₄ is the formula of the compound formed between D and C.
   Reason — D has 4 electrons in its outermost shell. C has 7 electrons in its outermost shell. Therefore, their valency is 4 and 1 respectively. So, 4 atoms of C will share their one electron each with one atom of D to form a compound. Hence, the formula of the compound is DC₄.

(b) D will exhibit catenation.
Reason — Electronic configuration of D (2, 4) suggests that it is Carbon. Carbon exhibits catenation to the maximum extent due to tetra-covalency of carbon and greater strength of carbon-carbon bond.

Choose the correct answer from the list given below:

$\boxed{\text{zinc blende}, \text{C}_2\text{H}_2, \text{calamine, CH, haematite}}$

(a) The ore which can be concentrated by magnetic separation.

(b) Empirical formula of Ethyne.

Answer

(a) Haematite
Reason — Haematite is an iron ore that can be concentrated by magnetic separation because it contains iron, which is magnetic.

(b) Molecular formula of Ethyne is C₂H₂. The simplest whole-number ratio of carbon to hydrogen in Ethyne is 1:1. Therefore, the empirical formula of Ethyne is CH.

Give balanced equation for the following reactions:

(a) Copper reacts with concentrated Nitric acid.

(b) Aluminium nitride is treated with warm water.

Answer

(a) Cu + 4HNO₃ (conc.) ⟶ Cu(NO₃)₂ + 2NO₂ + 2H₂O

(b) AlN + 3H₂O ⟶ Al(OH)₃ + NH₃

Match the salts underlined in Column A with the most suitable method of preparation given in Column B.

Answer

Hydrogen chloride gas is prepared in the laboratory by the action of concentrated sulphuric acid on sodium chloride.

(a) Give balanced chemical equation for the above reaction.

(b) State the method of collection of the gas formed above.

(c) What is the property of sulphuric acid that makes it a suitable reagent for the reaction?

Answer

(a) NaCl + H₂SO₄ $\xrightarrow{\text{\textless 200°C}}$ NaHSO₄ + HCl↑

(b) HCl gas formed is collected by upward displacement of air method.

(c) As conc. H₂SO₄ is non-volatile and has a high boiling point, therefore, it displaces the volatile hydrogen chloride from the salt sodium chloride. Hence, conc. H₂SO₄ is used as a reactant in the laboratory preparation of HCl from sodium chloride.
Conc. nitric acid cannot be used in place of conc. H₂SO₄ since it is volatile and may volatize out along with the hydrogen chloride.