These essential MCQ questions are selected from the most important topics in ICSE Class 10 Chemistry 2026 as per the latest CISCE syllabus. Sections include Periodic Table & Periodicity, Chemical Bonding, Acids, Bases & Salts, Electrolysis, Organic Chemistry, and Metallurgy. For truly unlimited daily MCQ practice, visit Vooo AI Education.
🧪 ICSE Class 10 Chemistry
1Across a period in the Modern Periodic Table, atomic radius generally:
Answer: B — Decreases
Across a period (left to right), atomic number increases, so nuclear charge increases. The number of shells remains the same but increased nuclear charge pulls electrons closer, reducing atomic radius. Down a group, atomic radius increases (more electron shells added). This trend explains why metals are on the left side of the periodic table (larger atoms, lower ionisation energy) and non-metals on the right (smaller atoms, higher electronegativity).
Across a period (left to right), atomic number increases, so nuclear charge increases. The number of shells remains the same but increased nuclear charge pulls electrons closer, reducing atomic radius. Down a group, atomic radius increases (more electron shells added). This trend explains why metals are on the left side of the periodic table (larger atoms, lower ionisation energy) and non-metals on the right (smaller atoms, higher electronegativity).
2An ionic bond is formed by:
Answer: B — Transfer of electrons
Ionic (electrovalent) bonds form when electrons are transferred from a metal atom (low ionisation energy) to a non-metal atom (high electron affinity), forming oppositely charged ions that attract each other. Example: Na donates one electron to Cl → Na⁺ and Cl⁻ → NaCl. Covalent bonds form by sharing of electrons (e.g., H₂, H₂O, CO₂). Ionic compounds have high melting points, conduct electricity when dissolved or molten, and are generally soluble in water.
Ionic (electrovalent) bonds form when electrons are transferred from a metal atom (low ionisation energy) to a non-metal atom (high electron affinity), forming oppositely charged ions that attract each other. Example: Na donates one electron to Cl → Na⁺ and Cl⁻ → NaCl. Covalent bonds form by sharing of electrons (e.g., H₂, H₂O, CO₂). Ionic compounds have high melting points, conduct electricity when dissolved or molten, and are generally soluble in water.
3Which of the following is a strong acid?
Answer: C — Sulphuric acid (H₂SO₄)
Strong acids completely dissociate into ions in water. The three common strong mineral acids in ICSE are H₂SO₄ (sulphuric acid), HCl (hydrochloric acid), and HNO₃ (nitric acid). Acetic acid, carbonic acid, and formic acid are weak acids that partially dissociate. Concentrated H₂SO₄ is also a dehydrating agent and oxidising agent. It produces SO₂ with copper and NO₂ with metals higher in the reactivity series.
Strong acids completely dissociate into ions in water. The three common strong mineral acids in ICSE are H₂SO₄ (sulphuric acid), HCl (hydrochloric acid), and HNO₃ (nitric acid). Acetic acid, carbonic acid, and formic acid are weak acids that partially dissociate. Concentrated H₂SO₄ is also a dehydrating agent and oxidising agent. It produces SO₂ with copper and NO₂ with metals higher in the reactivity series.
4During electrolysis of acidified water, which gas is released at the cathode?
Answer: B — Hydrogen
In electrolysis of acidified water (dilute H₂SO₄): at cathode (negative electrode), H⁺ ions are discharged → 2H⁺ + 2e⁻ → H₂↑; at anode (positive electrode), OH⁻ ions are discharged → 4OH⁻ → 2H₂O + O₂↑. Volume ratio of H₂:O₂ = 2:1. Cathode = reduction (gain of electrons); Anode = oxidation (loss of electrons). Electrolysis is used in electroplating and extraction of metals like aluminium and sodium.
In electrolysis of acidified water (dilute H₂SO₄): at cathode (negative electrode), H⁺ ions are discharged → 2H⁺ + 2e⁻ → H₂↑; at anode (positive electrode), OH⁻ ions are discharged → 4OH⁻ → 2H₂O + O₂↑. Volume ratio of H₂:O₂ = 2:1. Cathode = reduction (gain of electrons); Anode = oxidation (loss of electrons). Electrolysis is used in electroplating and extraction of metals like aluminium and sodium.
5The general formula for alkanes is:
Answer: B — CₙH₂ₙ₊₂
Alkanes (saturated hydrocarbons) have general formula CₙH₂ₙ₊₂. Examples: methane CH₄ (n=1), ethane C₂H₆ (n=2), propane C₃H₈ (n=3). Alkenes (one C=C double bond): CₙH₂ₙ. Alkynes (one C≡C triple bond): CₙH₂ₙ₋₂. Alkanes undergo substitution reactions. Alkenes undergo addition reactions (more reactive due to double bond). Benzene (C₆H₆) is an aromatic compound with a special ring structure.
Alkanes (saturated hydrocarbons) have general formula CₙH₂ₙ₊₂. Examples: methane CH₄ (n=1), ethane C₂H₆ (n=2), propane C₃H₈ (n=3). Alkenes (one C=C double bond): CₙH₂ₙ. Alkynes (one C≡C triple bond): CₙH₂ₙ₋₂. Alkanes undergo substitution reactions. Alkenes undergo addition reactions (more reactive due to double bond). Benzene (C₆H₆) is an aromatic compound with a special ring structure.
6Aluminium is extracted from its ore by:
Answer: C — Electrolytic reduction
Aluminium is extracted from bauxite (Al₂O₃) by electrolytic reduction (Hall-Héroult process) because Al is too reactive to be reduced by carbon or hydrogen. Molten aluminium oxide is electrolysed using carbon electrodes: Al³⁺ ions are reduced at the cathode; O²⁻ ions are oxidised at the anode (which burns away). Metals low in reactivity (Cu, Ag, Au) occur native or are extracted by simple heating. Iron is extracted by reduction with coke in a blast furnace.
Aluminium is extracted from bauxite (Al₂O₃) by electrolytic reduction (Hall-Héroult process) because Al is too reactive to be reduced by carbon or hydrogen. Molten aluminium oxide is electrolysed using carbon electrodes: Al³⁺ ions are reduced at the cathode; O²⁻ ions are oxidised at the anode (which burns away). Metals low in reactivity (Cu, Ag, Au) occur native or are extracted by simple heating. Iron is extracted by reduction with coke in a blast furnace.
7The pH of a neutral solution at 25°C is:
Answer: C — 7
pH is the negative logarithm of hydrogen ion concentration: pH = -log[H⁺]. Pure water at 25°C has pH = 7 (neutral). Acidic solutions: pH < 7 (more H⁺ ions). Basic/alkaline solutions: pH > 7 (more OH⁻ ions). pH 0 = very strong acid; pH 14 = very strong base. Indicators: litmus (red in acid, blue in base), phenolphthalein (colourless in acid, pink in base), methyl orange (red in acid, yellow in base). Universal indicator gives a range of colours.
pH is the negative logarithm of hydrogen ion concentration: pH = -log[H⁺]. Pure water at 25°C has pH = 7 (neutral). Acidic solutions: pH < 7 (more H⁺ ions). Basic/alkaline solutions: pH > 7 (more OH⁻ ions). pH 0 = very strong acid; pH 14 = very strong base. Indicators: litmus (red in acid, blue in base), phenolphthalein (colourless in acid, pink in base), methyl orange (red in acid, yellow in base). Universal indicator gives a range of colours.
8The process of coating a metal object with a thin layer of another metal using electrolysis is called:
Answer: C — Electroplating
Electroplating uses electrolysis to deposit a thin layer of metal on an object. The object to be plated is the cathode; the plating metal is the anode; the electrolyte is a solution of the plating metal's salt. Uses: chrome plating (cars), silver plating (cutlery), gold plating (jewellery), tin plating (food cans). Galvanisation is coating iron/steel with zinc by dipping in molten zinc (not electrolysis). Anodising is an electrochemical process that thickens the natural oxide layer on aluminium.
Electroplating uses electrolysis to deposit a thin layer of metal on an object. The object to be plated is the cathode; the plating metal is the anode; the electrolyte is a solution of the plating metal's salt. Uses: chrome plating (cars), silver plating (cutlery), gold plating (jewellery), tin plating (food cans). Galvanisation is coating iron/steel with zinc by dipping in molten zinc (not electrolysis). Anodising is an electrochemical process that thickens the natural oxide layer on aluminium.
9Bleaching powder is produced by passing chlorine over:
Answer: A/C — Dry slaked lime [Ca(OH)₂]
Bleaching powder (calcium hypochlorite, Ca(OCl)Cl) is manufactured by passing chlorine gas over dry slaked lime (Ca(OH)₂) at 40°C: Ca(OH)₂ + Cl₂ → Ca(OCl)Cl + H₂O. It releases nascent oxygen when treated with dilute acid, causing bleaching. Uses: bleaching cotton and linen, disinfecting drinking water and swimming pools, disinfecting sewage. It loses bleaching power on exposure to air due to slow oxidation. It should be stored in airtight containers.
Bleaching powder (calcium hypochlorite, Ca(OCl)Cl) is manufactured by passing chlorine gas over dry slaked lime (Ca(OH)₂) at 40°C: Ca(OH)₂ + Cl₂ → Ca(OCl)Cl + H₂O. It releases nascent oxygen when treated with dilute acid, causing bleaching. Uses: bleaching cotton and linen, disinfecting drinking water and swimming pools, disinfecting sewage. It loses bleaching power on exposure to air due to slow oxidation. It should be stored in airtight containers.
10Which of the following is an example of a double displacement reaction?
Answer: C — AgNO₃ + NaCl → AgCl↓ + NaNO₃
Double displacement (metathesis) reactions involve exchange of ions between two compounds. AgNO₃ + NaCl → AgCl↓ + NaNO₃: Ag⁺ and Na⁺ swap partners, forming a white precipitate of AgCl (insoluble). This is also a precipitation reaction. Zn + CuSO₄ is a single displacement (Zn displaces Cu). 2H₂ + O₂ is a combination/synthesis reaction. CaCO₃ → CaO + CO₂ is a decomposition reaction. Recognising reaction types is a key ICSE Class 10 chemistry skill.
Double displacement (metathesis) reactions involve exchange of ions between two compounds. AgNO₃ + NaCl → AgCl↓ + NaNO₃: Ag⁺ and Na⁺ swap partners, forming a white precipitate of AgCl (insoluble). This is also a precipitation reaction. Zn + CuSO₄ is a single displacement (Zn displaces Cu). 2H₂ + O₂ is a combination/synthesis reaction. CaCO₃ → CaO + CO₂ is a decomposition reaction. Recognising reaction types is a key ICSE Class 10 chemistry skill.
Ready to score top marks in ICSE Class 10 Chemistry?
Get free daily ICSE Class 10 Chemistry MCQs. Unlimited practice starts from just ₹120/month.
See Plans — Starts at ₹120