Solved 2023 Question Paper ICSE Class 10 Chemistry
Solutions for Chemistry, Class 10, ICSE
Section A 40 Marks
20 questionsAnswer:
Lithium
Reason — The given elements belong to the second period and Lithium is the first element of second period. Atomic size decreases from left to right in a period hence, Lithium will have the largest atomic radius.
Answer:
Ag - 1e- ⟶ Ag1+
Reason — During electroplating of an article with silver, the silver anode loses electrons to give Ag1+ ions in the solution.
Answer:
Cu(OH)2
Reason — Cu(OH)2 reacts with a solution of excess ammonium hydroxide to form a deep blue solution of tetrammine copper [II] sulphate.
Cu(OH)2 + (NH4)2SO4 + 2NH4OH ⟶ [Cu(NH3)4]SO4 + 4H2O
Answer:
concentrated sulphuric acid
Reason — Concentrated Sulphuric acid only removes the moisture content of HCl gas but does not react with it. Hence, it is used as a drying agent for HCl gas.
Answer:
Zinc nitrate
Reason —
Zinc nitrate decomposes to produces zinc oxide, which is yellow when hot and white when cold
Answer:
Non-volatile acid property
Reason — Concentrated sulphuric acid has a high boiling point, hence it is used to prepare hydrogen chloride gas from potassium chloride.
Match the Column A with Column B:
Column A | Column B |
---|---|
(a) Sodium Chloride | 1. has two shared pair of electrons |
(b) Methane | 2. has high melting and boiling points |
(c) Hydrogen chloride gas | 3. a greenhouse gas |
(d) Oxidation reaction | 4. has low melting and boiling points |
(e) Water | 5. Zn - 2e- ⟶ Zn2+ |
6. S + 2e- ⟶ S2- |
Answer:
Column A | Column B |
---|---|
(a) Sodium Chloride | 2. has high melting and boiling points |
(b) Methane | 3. a greenhouse gas |
(c) Hydrogen chloride gas | 4. has low melting and boiling points |
(d) Oxidation reaction | 5. Zn - 2e- ⟶ Zn2+ |
(e) Water | 1. has two shared pair of electrons |
The following sketch illustrates the process of conversion of Alumina to Aluminium:
Study the diagram and answer the following:

(a) Name the constituent of the electrolyte mixture which has a divalent metal in it.
(b) Name the powdered substance 'X' sprinkled on the surface of the electrolyte mixture.
(c) What is the name of the process?
(d) Write the reactions taking place at the electrodes 'Y' (anode) and 'Z' (cathode) respectively.
Answer:
(a) Fluorspar [CaF2]
(b) Powdered coke
(c) Hall-Heroult's process
(d) Reactions taking place at the electrodes 'Y' (anode) and 'Z' (cathode):
At anode:
6O2- - 12e- ⟶ 6[O]
3O + 3O ⟶ 3O2
At cathode:
4Al3+ + 12e- ⟶ 4Al
Fill in the blanks with the choices given in the brackets:
(a) Metals are good ............... [oxidizing agents /reducing agents]
(b) Non-polar covalent compounds are ............... [good / bad] conductors of heat and electricity.
(c) Higher the pH value of a solution, the more is ............... [acidic / alkaline] it is.
(d) ............... [Silver chloride / Lead chloride] is a white precipitate that is soluble in excess of Ammonium hydroxide solution.
(e) Conversion of ethene to ethane is an example of ............... . [hydration / hydrogenation]
Answer:
(a) Metals are good reducing agents
(b) Non-polar covalent compounds are bad conductors of heat and electricity.
(c) Higher the pH value of a solution, the more alkaline it is.
(d) Silver chloride is a white precipitate that is soluble in excess of Ammonium hydroxide solution.
(e) Conversion of ethene to ethane is an example of hydrogenation.
State the terms/process for the following:
(a) The energy released when an atom in the gaseous state accepts an electron to form an anion.
(b) Tendency of an element to form chains of identical atoms.
(c) The name of the process by which Ammonia is manufactured on a large scale.
(d) A type of salt formed by partial replacement of hydroxyl radicals with an acid radical.
(e) The ratio of the mass of a certain volume of gas to the same volume of hydrogen measured under the same conditions of temperature and pressure.
Answer:
(a) Electron affinity
(b) Catenation
(c) Haber’s process
(d) Basic salt
(e) Vapour Density
Answer:
(a) Structural formula
1. 2-chlorobutane

2. Methanal

3. But-2-yne

(b) IUPAC names are:
- Ethanoic acid
- Butan-2-ol
Section B 40 Marks
24 questionsIdentify the cation in each of the following cases:
(a) Ammonium hydroxide solution when added to Solution B gives a white precipitate which does not dissolve in excess of ammonium hydroxide solution.
(b) Sodium hydroxide solution when added to Solution C gives a white precipitate which is insoluble in excess of sodium hydroxide solution.
Answer:
(a) Pb2+
Reason — When ammonium hydroxide solution is added to lead nitrate, it forms a chalky white precipitate of lead hydroxide [Pb(OH)2] which is insoluble in excess of ammonium hydroxide.
Pb(NO3)2 + 2NH4OH ⟶ 2NH4NO3 + Pb(OH)2
(b) Ca2+
Reason — When sodium hydroxide solution is added to calcium nitrate, a white precipitate of calcium hydroxide is obtained which is insoluble in excess of sodium hydroxide solution.
Ca(NO3)2 + 2NaOH ⟶ Ca(OH)2 ↓ + 2NaNO3
Fill in the blanks by choosing the correct answer from the brackets:
(a) During electrolysis, the compound ............... in its molten state liberates reddish brown fumes at the anode. [NaCl/PbBr2]
(b) The ion which could be discharged most readily during electrolysis is ............... [Fe2+/Cu2+]
Answer:
(a) During electrolysis, the compound PbBr2 in its molten state liberates reddish brown fumes at the anode.
(b) The ion which could be discharged most readily during electrolysis is Cu2+
Answer:
(a) K > Ca > Mg > Al
Reason — According to the electrochemical series metals at the top of the series are most reactive and the reactivity decreases down the group.
(b) Be < C < N < O
Reason — Across a period, left to right in a periodic table, the non-metallic character increases.
(c) F > P > Si > Be
Reason — The valence electrons decreases from right to left in the periodic table.
Answer:
(a) Quicklime [CaO] is alkaline in nature and it reacts with HCl forming the respective chloride. Hence, it can't be used as a drying agent for Hydrogen chloride gas.
CaO + 2HCl ⟶ CaCl2 + H2O
(b) As ammonia gas is highly soluble in water, therefore, it is not collected over water.
Answer:
[By Lussac's law]
(i) To calculate the volume of CO2 formed :
Hence, volume of carbon dioxide formed = 160 ml
(ii) To calculate the volume of unused O2 :
Unused oxygen = 300 - 280 = 20 ml.
Hence, volume of unused oxygen = 20 ml
Therefore, the resultant gaseous mixture consists of 160 ml of carbon dioxide and 20 ml of unused oxygen.
Answer:
(a) Mg3N2 + 6H2O ⟶ 3Mg(OH)2 + 2NH3
(b) As nitrides are expensive, hence the method is seldom used.
(c) Ways in which ammonia gas can be identified is:
- It has a sharp characteristic odour.
- It turns:
- moist red litmus blue,
- moist turmeric paper brown,
- phenolphthalein solution pink.
- When a glass rod dipped in conc. HCl is brought near the mouth of the jar containing NH3, dense white fumes of ammonium chloride are formed.
NH3 + HCl ⟶ NH4Cl
Study the following observations and name the anions present in each of the reactions.
(a) When a crystalline solid 'P' is warmed with concentrated H2SO4 and copper turnings a reddish brown gas is released.
(b) When few drops of dilute sulphuric acid is added to Salt 'R' and heated, a colourless gas is released which turns moist lead acetate paper silvery black.
(c) When few drops of barium nitrate solution is added to the salt solution 'Q', a white precipitate is formed which is insoluble in HCl.
Answer:
(a) Nitrate [NO3-]
(b) Sulphide [S2-]
(c) Sulphate [SO42-]
Answer:
(a) Electronegativity — The tendency of an atom in a molecule to attract the shared pair of electrons towards itself is called its electronegativity.
(b) Gay-Lussac's Law of combining volumes — When gases react, they do so in volumes which bear a simple ratio to one another, and to the volume of the gaseous product, provided that all the volumes are measured at the same temperature and pressure.
Answer:
Empirical formula is CHCl2
Empirical formula weight = 12 + 1 + 2[35.5] = 12 + 1 + 71 = 84
Molecular weight = 168
So, molecular formula = 2(CHCl2) = C2H2Cl4
Choose the substances given in the box below to answer the following questions:
Iron | Magnesium sulphite | Zinc | Sodium sulphide |
Lead | Ferric chloride | Copper | Ferrous sulphate |
(a) The metal that will not produce hydrogen gas when reacted with dilute acids.
(b) The compound that will produce sulphur dioxide gas when reacted with dilute HCl.
(c) The solution of this compound produces dirty green precipitate with NaOH.
Answer:
(a) Copper
(b) Sodium Sulphite
(c) Ferrous Sulphate
Answer:
(a) When a few drops of sodium hydroxide solution are added to the copper nitrate solution, light blue coloured ppt. of Cu(OH)2 is obtained which is insoluble with excess NaOH.
(b) Ammonia burns in the atmosphere of excess oxygen with a greenish yellow flame, forming nitrogen and water vapour.
(c) Buff yellow PbO is reduced to greyish metallic lead.
Answer:
(a) Isomers
(b) Homologous series
Answer:
(a) On moving down the group, atomic size, as well as, nuclear charge increases. However, the effect of increase in atomic size dominates over the effect of increase in nuclear charge. Hence, ionization potential decreases down the group.
(b) There is a strong electrostatic force of attraction between the oppositely charged ions of the ionic compounds that keeps ions in fixed position in solid state. Due to this immobility of ions, ionic compounds do not conduct electricity in solid state.
Answer:
(a) Molecular weight of Ca(H2PO4)2
= 40 + 2[2(1) + 31 + 4(16)]
= 40 + 2[2 + 31 + 64]
= 40 + 2[97]
= 40 + 194
= 234 g
234 g of Ca(H2PO4)2 contains 62 g of P
∴ 100 g of Ca(H2PO4)2 will contain = x 100 = 26.49% = 26.5%
Hence, 26.5% phosphorous is present in superphosphate Ca(H2PO4)2
(b) Given,
Molecular Formula = C8H18 = (C4H9)2
Molecular formula = n[Empirical formula]
∴ n = 2
Hence, Empirical formula = C4H9
Answer:
(a) Impure block of copper.
(b) Pure copper is deposited on the thin sheet of pure copper placed at the cathode.
(c) Cu2+ + 2e- ⟶ Cu
Answer:
(a) Molecular weight of C2H2 = 2[12] + 2[1] = 26
Molecular weight of C3H6 = 3[12] + 6[1] = 42
Molecular weight of CH4 = 12 + 4[1] = 16
Molecular weight of C2H4 = 2[12] + 4[1] = 28
Hence, increasing order of molecular weights is :
CH4 < C2H2 < C2H4 < C3H6
(b) Ag+, Cu2+, Zn2+, Na+
Answer:
(a) Conc. H2SO4 dehydrates sucrose to a black spongy charged mass of carbon sugar charcoal.
The blue coloured hydrous copper sulphate changes to white anhydrous copper sulphate as the water of crystallization is removed.
(b) Sulphuric acid forms sulphate salts whereas hydrochloric acid forms chloride salts.
Answer:
(a) Ammonia to nitric oxide using oxygen and platinum catalyst.
(b) Sodium hydroxide to sodium sulphate using sulphuric acid.
2NaOH + H2SO4 ⟶ Na2SO4 + 2H2O
(c) Ferrous sulphide to hydrogen sulphide using hydrochloric acid
FeS + 2HCl ⟶ FeCl2 + H2S