ICSE Class 10 Science — Chemistry — Important Questions
Question types and patterns from official CISCE board papers 2023, 2024, and 2025. Every topic below has appeared in at least one recent board examination.
Section A — Compulsory (Questions 1–2, 40 marks)
Q1: 15 MCQs (1 mark each). Q2: Five parts of 5 marks each — fill-in, match, equations, naming, structural formulae.
Organic Chemistry — Identification
Q1 MCQ every year- ·Identify saturated hydrocarbon from molecular formula (CₙH₂ₙ₊₂)
- ·Identify homologous series from set of compounds
- ·Calculate molecular formula from vapour density
Metallurgy — Ores and Reduction
Q1 MCQ every year- ·Metal whose oxide can be reduced by common reducing agents (copper)
- ·Ore concentrated by magnetic separation (haematite)
Periodic Table — Trends
Q1 MCQ + Q3/Q5 every year- ·Tendency to lose electrons increases down group (metals become more reactive)
- ·Identify element with highest ionisation potential from a set: Ne > F > O; Cl > Mg > Al
Chemical Bonding — Electron Dot
Q1 MCQ + Q7 every year- ·Electronic configuration of atoms in covalent molecule AB₂
- ·Ions with same electronic configuration (isoelectronic pairs)
- ·Draw dot-cross for MgCl₂ (ionic), HCl (covalent), NH₄⁺ (coordinate)
Electrolysis
Q1 MCQ + Q7 every year- ·CuSO₄ with Cu electrodes — positive electrode loses mass (NOT: number of Cu²⁺ ions decreases — this is TRUE)
- ·Anode = oxidising electrode (loses electrons); Graphite preferred in molten PbBr₂ (inert, non-reactive)
Acids, Bases, Salts — Reactions
Q1 MCQ + Q2 every year- ·Best reagents to prepare PbSO₄: Na₂SO₄ + Pb(NO₃)₂ (precipitation)
- ·Sulphuric acid acting as oxidising agent (S + 2H₂SO₄ → 3SO₂ + 2H₂O)
Mole Concept — Gay Lussac + Calculations
Q4 every year- ·Find vapour density and molecular weight from mass of gas in same cylinder as H₂
- ·Calculate mass of H₂SO₄ and volume of SO₂ at STP from mass of Mg reacted
- ·Mole calculations from percentage composition — find empirical and molecular formula
Ammonia
Q2 every year — fill-in / match / equation- ·Lab preparation from aluminium nitride + water; identify drying agent (CaO)
- ·Catalysts match: N₂+3H₂→NH₃ (Fe), 4NH₃+5O₂→4NO (Pt), 2SO₂+O₂→2SO₃ (V₂O₅), C₂H₄+H₂ (Ni)
Organic — Structural Formulae and IUPAC Names
Q2 + Q6 every year- ·Draw structural formula of 2-methyl propene, butanal
- ·Give IUPAC name of given structural formulae
- ·Identify which organic compounds are from same homologous series
Salts — Analytical Chemistry
Q2 fill-in + Q5 every year- ·CuSO₄ + NH₄OH excess → deep blue solution (soluble); Pb salt + NH₄OH excess → insoluble
- ·Distinguish NH₄Cl from NaCl using alkali; distinguish Zn(NO₃)₂ from Ca(NO₃)₂ using excess NaOH
Section B — Attempt any 4 of 5 (Questions 3–8, 40 marks)
Each question has 3–4 parts.
Periodic Table + Bonding — Short Theory
Section B every year (Q3/Q5)- ·State period of element with atomic number 14; formula of compound with element of Z=8
- ·Valency of element in group VIIA; which element exhibits catenation
Electrolysis Calculations + Theory
Section B every year (Q7)- ·Why dilute H₂SO₄ added to water (increases conductivity/ion concentration)
- ·Write cathode reaction, describe anode observation in electrolysis of acidulated water
Organic — Properties and Equations
Section B every year (Q4/Q6)- ·Complete and balance CH₃COONa + NaOH → CH₄ + Na₂CO₃ (CaO, Δ)
- ·Name gas produced: Cu + conc. HNO₃ (NO₂), NH₃ burnt in O₂ (NO), FeS + dil. HCl (H₂S)
Study of Compounds — HCl, H₂SO₄, HNO₃
Section B every year (Q7/Q8)- ·Copper + conc. HNO₃ → reddish-brown gas (NO₂); write balanced equation
- ·Concentrated H₂SO₄ acting as dehydrating agent; oxidising agent with C and S
Salts — Preparation Methods
Section B every year (Q8)- ·Choose method for PbCl₂ (precipitation/R), FeCl₃ (direct combination/S), Na₂SO₄ (neutralisation/Q)
Source: All patterns derived from official CISCE ICSE Class 10 board examination papers (2023, 2024, 2025) downloaded from cisce.org. For the actual question papers, view the Science — Chemistry Previous Year Papers.