Question 1

Question 1(i)Unsaturated hydrocarbons undergo:Addition reactionSubstitution reactionOxidation reactionRedox reaction

Accepted Answer

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

Question 2

Question 1(iv)The metal hydroxide which reacts with both acids and alkalis to form salt and water is:Calcium hydroxideMagnesium hydroxideAluminium hydroxideFerric hydroxide

Accepted Answer

Aluminium hydroxideReason — 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.

Question 3

Question 1(vi)Conversion of Ethanol to Ethene by the action of concentrated sulphuric acid involves:DehydrationDehydrogenationDehydrohalogenationHydrolysis

Accepted Answer

DehydrationReason — Dehydration involves elimination of elements of water from alcohol. Conc. sulphuric acid act as dehydrating agent.C2H5OH ethyl alcohol→170°CConc. H2SO4[excess]C2H4ethene+H2O \underset{	ext{ ethyl alcohol}}{	ext{C}_2	ext{H}_5	ext{OH}} \xrightarrow[170\degree	ext{C}]{	ext{Conc. H}_2	ext{SO}_4	ext{[excess]}} \underset{ 	ext{ethene}}{	ext{C}_2	ext{H}_4} + 	ext{H}_2	ext{O}\ ethyl alcoholC2​H5​OH​Conc. H2​SO4​[excess]170°C​etheneC2​H4​​+H2​O The products formed are ethene and water.

Question 4

Question 1(viii)Electron Affinity is maximum in:MgArLiBr

Accepted Answer

BrReason — 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.

Question 5

Question 1(ix)The compound that is not a constituent of the electrolytic mixture used in the Hall-Heroult's process is:Al2O3NaAlO2Na3AlF6CaF2

Accepted Answer

CaF2Reason — Calcium fluoride is not part of the standard Hall-Heroult electrolytic mixture.

Question 6

Question 1(xiv)In the molecule of water, oxygen atom has:One shared pair of electrons.Three shared pairs of electrons.Two lone pairs of electrons.One lone pair of electrons

Accepted Answer

Two lone pairs of electronsReason — 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 :

Question 7

Question 1(xv)A mineral from which the metal can be extracted economically and conveniently is known as:MatrixOreFluxAlloy

Accepted Answer

OreReason — 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.

Question 8

Question 2(v)(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:3-methyl pentanepropynemethanal

Accepted Answer

(a) IUPAC names are:2,3-Dichloropentane1-Propanoic acid(b) Structural formula1. 3-methyl pentane2. Propyne3. Methanal

Question 9

Question 3(ii)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.

Accepted 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 (CO32-).(b) The brown ring test indicates the presence of nitrate ions (NO3-).

Question 10

Question 3(iii)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?

Accepted 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.

Question 11

Question 4(i)Define the following terms:(a) Molar volume(b) Normal salt

Accepted 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].

Question 12

Question 4(iii)Complete and balance the following equations:(a) Al2O3 + 2NaOH ⟶(b) C2H5COONa + NaOH ⟶CaoΔ\overset{	ext{Δ}}{\underset{	ext{Cao}}{\longrightarrow}}Cao⟶​Δ​(c) C2H4Br2 + alcoholic KOH ⟶Δ\overset{	ext{Δ}}{\longrightarrow}⟶Δ​

Accepted Answer

(a) Al2O3 + 2NaOH ⟶ 2NaAlO2 + H2O(b) C2H5COONa + NaOH ⟶CaoΔ\overset{	ext{Δ}}{\underset{	ext{Cao}}{\longrightarrow}}Cao⟶​Δ​ C2H6 + Na2CO3(c) C2H4Br2 + 2KOH (alcoholic) ⟶Δ\overset{	ext{Δ}}{\longrightarrow}⟶Δ​ C2H2 + 2KBr + 2H2O

Question 13

Question 5(ii)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)

Accepted 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↓ + 2HClWhen 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.

Question 14

Question 5(iii)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?

Accepted 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

Question 15

Question 5(iv)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.

Accepted Answer

(a) Carbon dioxideCH4 + 2O2 ⟶ CO2 + 2H2O(b) Carbon dioxideCuCO3 ⟶ CuO + CO2(c) ChlorineMnO2 + 4HCl ⟶ MnCl2 + 2H2O + Cl2

Question 16

Question 6(i)X - HCl ⇋ H1+ + Cl- (in solution state)Y - PbBr2 ⇋ Pb2+ + 2Br1- (in molten state)From the above reactions X or Y, identify the reaction which exhibits:(a) electrolytic dissociation(b) ionization

Accepted Answer

(a) Y is electrolytic dissociation.Reason — PbBr2 is an electrovalent compound and its contains lead [Pb2+] and bromide [Br1-] 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.

Question 17

Question 6(iv)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.

Accepted Answer

(a) Hydrogen(b) Sulphur(c) ChlorineQuestion 7(i)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.(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).Question 7(ii)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].(a) Carbon tetrachloride is a non-polar covalent molecule.(b) During electrolysis of acidulated water, the gas liberated at the anode is oxygen .

Question 18

Question 7(iii)Ammonia burns in oxygen as shown below.4NH3 + 3O2 ⟶ 2N2 + 6H2OIf 240 cc of ammonia is burnt in 300 cc of oxygen, find out the composition of the resultant gaseous mixture at room temperature.

Accepted Answer

According to the given equation:For N24 vol. of NH3 produce 2 vol. of N2∴ 240 cc of NH3 will produce = 2×2404\dfrac{2 	imes 240}{4}42×240​ = 120 cc of N2For O24 vol. of NH3 reacts with 3 vol. of O2∴ 240 cc of NH3 will react with = 3×2404\dfrac{3 	imes 240}{4}43×240​ = 180 cc of O2.Amount of unused Oxygen = 300 cc - 180 cc = 120 ccHence, composition of the resultant gaseous mixture at room temperature is 120 cc of O2 + 120 cc of N2

Question 19

Question 7(iv)The following table shows the electronic configuration of the atoms A, B, C and D.ElementABCDElectronic configuration2, 8, 8, 22, 62, 8, 72, 4(a) Write the formula of the compound formed between:A and BD and C(b) Which of the above elements will exhibit catenation?

Accepted Answer

(a)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.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.

Question 20

Question 8(i)Choose the correct answer from the list given below:zinc blende,C2H2,calamine, CH, haematite\boxed{	ext{zinc blende}, 	ext{C}_2	ext{H}_2, 	ext{calamine, CH, haematite}}zinc blende,C2​H2​,calamine, CH, haematite​(a) The ore which can be concentrated by magnetic separation.(b) Empirical formula of Ethyne.

Accepted Answer

(a) HaematiteReason — 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.

Solved 2024 Question Paper ICSE Class 10 Chemistry

Section A 40 Marks

Section B 40 Marks