These essential MCQ questions are selected from the most important topics in ICSE ISC Class 12 Chemistry Board Examination 2026. Sections include Organic Chemistry, Physical Chemistry, Inorganic Chemistry, Electrochemistry and Practical Chemistry as per the ISC syllabus. For truely unlimited daily MCQ practice, visit Vooo AI Education.
⚗️ ICSE Class 12 Chemistry
1Which bond is present in ethene (C₂H₄)?
Answer: C — Double bond
Ethene (C₂H₄) contains a carbon-carbon double bond (C=C). The carbon atoms are sp² hybridised. One bond is a sigma (σ) bond and the other is a pi (π) bond. The pi bond makes ethene reactive towards addition reactions.
Ethene (C₂H₄) contains a carbon-carbon double bond (C=C). The carbon atoms are sp² hybridised. One bond is a sigma (σ) bond and the other is a pi (π) bond. The pi bond makes ethene reactive towards addition reactions.
2Electrolysis of brine produces which gas at anode?
Answer: C — Chlorine
During electrolysis of brine (NaCl solution): Chlorine gas (Cl₂) is produced at the anode (oxidation), hydrogen gas (H₂) at the cathode (reduction), and sodium hydroxide (NaOH) forms in solution. This is the chlor-alkali process.
During electrolysis of brine (NaCl solution): Chlorine gas (Cl₂) is produced at the anode (oxidation), hydrogen gas (H₂) at the cathode (reduction), and sodium hydroxide (NaOH) forms in solution. This is the chlor-alkali process.
3Which reaction converts alkene to alkane?
Answer: C — Hydrogenation
Hydrogenation is the addition of hydrogen (H₂) across a double bond to convert an alkene into an alkane. For example: CH₂=CH₂ + H₂ → CH₃–CH₃. It requires a nickel, palladium or platinum catalyst and is an exothermic reaction.
Hydrogenation is the addition of hydrogen (H₂) across a double bond to convert an alkene into an alkane. For example: CH₂=CH₂ + H₂ → CH₃–CH₃. It requires a nickel, palladium or platinum catalyst and is an exothermic reaction.
4The shape of ammonia (NH₃) molecule is:
Answer: D — Trigonal pyramidal
Ammonia (NH₃) has a trigonal pyramidal shape. Nitrogen has sp³ hybridisation with 3 bond pairs and 1 lone pair. The lone pair repels the bond pairs, reducing the H-N-H angle to 107° (less than tetrahedral 109.5°).
Ammonia (NH₃) has a trigonal pyramidal shape. Nitrogen has sp³ hybridisation with 3 bond pairs and 1 lone pair. The lone pair repels the bond pairs, reducing the H-N-H angle to 107° (less than tetrahedral 109.5°).
5Which indicator is used in strong acid-weak base titration?
Answer: B — Methyl orange
Methyl orange (pH range 3.1–4.4) is used for strong acid–weak base titrations. Phenolphthalein (pH range 8.3–10.0) is used for strong base–weak acid titrations. The indicator chosen should change colour near the equivalence point of the titration.
Methyl orange (pH range 3.1–4.4) is used for strong acid–weak base titrations. Phenolphthalein (pH range 8.3–10.0) is used for strong base–weak acid titrations. The indicator chosen should change colour near the equivalence point of the titration.
6Enthalpy change in a reaction at constant pressure equals:
Answer: C — Heat absorbed or released
At constant pressure, ΔH = q_p (enthalpy change equals heat absorbed or released). Exothermic reactions have negative ΔH (heat released); endothermic reactions have positive ΔH (heat absorbed). This is the basis of thermochemistry.
At constant pressure, ΔH = q_p (enthalpy change equals heat absorbed or released). Exothermic reactions have negative ΔH (heat released); endothermic reactions have positive ΔH (heat absorbed). This is the basis of thermochemistry.
7The Wurtz reaction is used to prepare:
Answer: C — Higher alkanes
The Wurtz reaction uses alkyl halides with sodium metal in dry ether to produce higher alkanes: 2R–X + 2Na → R–R + 2NaX. For example, two molecules of methyl iodide give ethane. It is used to synthesise alkanes with even number of carbon atoms.
The Wurtz reaction uses alkyl halides with sodium metal in dry ether to produce higher alkanes: 2R–X + 2Na → R–R + 2NaX. For example, two molecules of methyl iodide give ethane. It is used to synthesise alkanes with even number of carbon atoms.
8Which metal is most electropositive?
Answer: C — Caesium
Caesium (Cs) is the most electropositive metal — it loses electrons most readily. Electropositive character increases down a group and decreases across a period. Caesium is the largest alkali metal and has the lowest ionisation energy among stable elements.
Caesium (Cs) is the most electropositive metal — it loses electrons most readily. Electropositive character increases down a group and decreases across a period. Caesium is the largest alkali metal and has the lowest ionisation energy among stable elements.
9Molar mass of sulphuric acid (H₂SO₄) is:
Answer: B — 98 g/mol
Molar mass of H₂SO₄ = 2(1) + 32 + 4(16) = 2 + 32 + 64 = 98 g/mol. Atomic masses: H=1, S=32, O=16. H₂SO₄ is a strong diprotic acid — it can donate two protons (H⁺ ions) per molecule.
Molar mass of H₂SO₄ = 2(1) + 32 + 4(16) = 2 + 32 + 64 = 98 g/mol. Atomic masses: H=1, S=32, O=16. H₂SO₄ is a strong diprotic acid — it can donate two protons (H⁺ ions) per molecule.
10Functional isomers of alcohols are:
Answer: A — Ethers
Alcohols (R–OH) and ethers (R–O–R) are functional isomers — they have the same molecular formula but different functional groups. For example, ethanol (C₂H₅OH) and dimethyl ether (CH₃OCH₃) both have molecular formula C₂H₆O.
Alcohols (R–OH) and ethers (R–O–R) are functional isomers — they have the same molecular formula but different functional groups. For example, ethanol (C₂H₅OH) and dimethyl ether (CH₃OCH₃) both have molecular formula C₂H₆O.
Ready to ace ICSE Class 12 Chemistry 2026?
Get free daily ICSE Class 12 Chemistry MCQs. Unlimited practice starts from just ₹120/month.
See Plans — Starts at ₹120