Frequently Asked MCQs in CBSE Class 12 Chemistry Exams
Frequently Asked MCQs in CBSE Class 12 Chemistry Exams (NCERT Based)
Course: CBSE Class 12 Chemistry
Section: Exam-Focused MCQs for CBSE Class 12 Chemistry
This set of 50 frequently asked MCQs is strictly based on the NCERT Class 12 Chemistry syllabus and compiled from commonly repeated CBSE board exam concepts. Each question is supported by a clear, concept-clearing explanation, making it ideal for board-oriented preparation, revision, and practice.
The MCQs are arranged section-wise to ensure balanced coverage of Physical, Inorganic, and Organic Chemistry, along with Biomolecules, Polymers, and Chemistry in Everyday Life.
Section A: Physical Chemistry (Most Repeated MCQs)
Q1. Raoult’s law is applicable to
(a) Ideal solutions
(b) Non-ideal solutions
(c) Colloidal solutions
(d) Electrolytic solutions
Answer: (a)
Explanation: Raoult’s law is valid only for ideal solutions where intermolecular forces between components are similar.
Q2. Molality is preferred over molarity in colligative properties because it
(a) Depends on volume
(b) Is temperature independent
(c) Is easier to calculate
(d) Uses litres of solution
Answer: (b)
Explanation: Molality depends on mass of solvent, which remains constant with temperature.
Q3. The van’t Hoff factor for CaCl₂ in aqueous solution is
(a) 1
(b) 2
(c) 3
(d) 4
Answer: (c)
Explanation: CaCl₂ dissociates into Ca²⁺ and 2Cl⁻ ions, giving three particles.
Q4. EMF of a galvanic cell is maximum when
(a) Current flows
(b) Reaction is at equilibrium
(c) No current flows
(d) Resistance is zero
Answer: (c)
Explanation: EMF is measured under open-circuit conditions.
Q5. The half-life of a first-order reaction depends on
(a) Initial concentration
(b) Rate constant
(c) Pressure
(d) Time
Answer: (b)
Explanation: Half-life of a first-order reaction is independent of initial concentration.
Q6. Unit of rate constant for a zero-order reaction is
(a) s⁻¹
(b) mol L⁻¹ s⁻¹
(c) L mol⁻¹ s⁻¹
(d) mol² L⁻² s⁻¹
Answer: (b)
Q7. According to Arrhenius equation, rate constant increases with
(a) Decrease in temperature
(b) Increase in activation energy
(c) Increase in temperature
(d) Decrease in concentration
Answer: (c)
Q8. Kohlrausch’s law is used to calculate
(a) pH of solution
(b) Limiting molar conductivity
(c) Cell constant
(d) Transport number
Answer: (b)
Section B: Inorganic Chemistry (Frequently Tested Concepts)
Q9. Variable oxidation states of transition metals are due to
(a) Large atomic size
(b) Partially filled d-orbitals
(c) High density
(d) Metallic bonding
Answer: (b)
Q10. Colour of transition metal ions is due to
(a) f–f transitions
(b) d–d transitions
(c) Charge transfer
(d) Metallic bonding
Answer: (b)
Q11. Lanthanoid contraction occurs because of
(a) High atomic mass
(b) Poor shielding by 4f electrons
(c) Metallic bonding
(d) High density
Answer: (b)
Q12. Coordination number of Fe in [Fe(CN)₆]³⁻ is
(a) 3
(b) 4
(c) 5
(d) 6
Answer: (d)
Q13. Oxalate ion acts as a
(a) Monodentate ligand
(b) Ambidentate ligand
(c) Bidentate ligand
(d) Neutral ligand
Answer: (c)
Q14. The geometry of SF₆ molecule is
(a) Tetrahedral
(b) Square planar
(c) Trigonal bipyramidal
(d) Octahedral
Answer: (d)
Q15. Element showing maximum catenation is
(a) Silicon
(b) Carbon
(c) Nitrogen
(d) Oxygen
Answer: (b)
Section C: Organic Chemistry (Most Asked Reaction MCQs)
Q16. SN1 reactions are favoured by
(a) Primary carbocations
(b) Secondary carbocations
(c) Tertiary carbocations
(d) Methyl carbocations
Answer: (c)
Q17. Lucas test is used to distinguish
(a) Aldehydes and ketones
(b) Phenols and ethers
(c) Primary, secondary and tertiary alcohols
(d) Amines
Answer: (c)
Q18. Phenol is more acidic than ethanol due to
(a) Inductive effect
(b) Resonance stabilisation
(c) Hydrogen bonding
(d) Molecular mass
Answer: (b)
Q19. Tollens’ reagent gives silver mirror with
(a) Ketones
(b) Aldehydes
(c) Alcohols
(d) Carboxylic acids
Answer: (b)
Q20. Cannizzaro reaction is shown by aldehydes
(a) With α-hydrogen
(b) Without α-hydrogen
(c) Aromatic only
(d) Aliphatic only
Answer: (b)
Q21. Aniline is less basic than methylamine because of
(a) +I effect
(b) –I effect
(c) Resonance
(d) Steric hindrance
Answer: (c)
Q22. Diazonium salts are prepared below 5 °C because they
(a) React slowly
(b) Are unstable at higher temperature
(c) Require excess acid
(d) Are endothermic
Answer: (b)
Section D: Biomolecules, Polymers & Everyday Chemistry
Q23. Glucose is a
(a) Disaccharide
(b) Polysaccharide
(c) Monosaccharide
(d) Glycoprotein
Answer: (c)
Q24. Proteins are polymers of
(a) Fatty acids
(b) Amino acids
(c) Nucleotides
(d) Glucose
Answer: (b)
Q25. Peptide bond is formed between
(a) Two sugars
(b) Two amino acids
(c) Two fatty acids
(d) Two nucleotides
Answer: (b)
Q26. Nylon-6,6 is formed by
(a) Addition polymerisation
(b) Condensation polymerisation
(c) Free radical polymerisation
(d) Copolymerisation
Answer: (b)
Q27. Buna-S is a copolymer of
(a) Butadiene and styrene
(b) Isoprene and styrene
(c) Ethene and propene
(d) Vinyl chloride and styrene
Answer: (a)
Q28. Analgesics are drugs used to
(a) Reduce fever
(b) Kill bacteria
(c) Relieve pain
(d) Induce sleep
Answer: (c)
Q29. Which of the following is a non-narcotic analgesic?
(a) Morphine
(b) Codeine
(c) Aspirin
(d) Heroin
Answer: (c)
Q30. Antibiotics are ineffective against
(a) Bacteria
(b) Fungi
(c) Viruses
(d) Protozoa
Answer: (c)
Section E: High-Frequency Board Logic MCQs
Q31. Zero-order reaction shows linear plot of
(a) log[A] vs t
(b) 1/[A] vs t
(c) [A] vs t
(d) k vs t
Answer: (c)
Q32. Chelation increases stability of complexes due to
(a) Size effect
(b) Entropy increase
(c) Charge increase
(d) Steric effect
Answer: (b)
Q33. Monomer of Teflon is
(a) Ethene
(b) Styrene
(c) Vinyl chloride
(d) Tetrafluoroethylene
Answer: (d)
Q34. Vitamin C is
(a) Fat-soluble
(b) Water-soluble
(c) Hormone
(d) Enzyme
Answer: (b)
Q35. Insulin is a
(a) Vitamin
(b) Lipid
(c) Hormone
(d) Carbohydrate
Answer: (c)
Q36. Hydrophilic part of soap is
(a) Hydrocarbon chain
(b) –COO⁻ group
(c) Alkyl group
(d) Benzene ring
Answer: (b)
Q37. Strongest acid among hydrogen halides is
(a) HF
(b) HCl
(c) HBr
(d) HI
Answer: (d)
Q38. Most electronegative element is
(a) Oxygen
(b) Nitrogen
(c) Chlorine
(d) Fluorine
Answer: (d)
Q39. Approximate pH of human blood is
(a) 5.6
(b) 6.8
(c) 7.4
(d) 8.5
Answer: (c)
Q40. Diazepam is classified as a
(a) Antibiotic
(b) Analgesic
(c) Tranquilizer
(d) Antipyretic
Answer: (c)
Section E: Ultra-Frequently Asked Board Facts (Q41–Q50)
Q41. The correct increasing order of reducing power of Zn, Cu and Ag is
(a) Ag < Cu < Zn
(b) Cu < Zn < Ag
(c) Zn < Cu < Ag
(d) Ag < Zn < Cu
Answer: (c)
Explanation: Reducing power decreases with increase in standard reduction potential (E°). Since E° increases from Zn → Cu → Ag, reducing power decreases in the same order.
Q42. Which substance exhibits maximum hydrogen bonding?
(a) NH₃
(b) HF
(c) H₂O
(d) CH₄
Answer: (c)
Explanation: Water molecules can form up to four hydrogen bonds per molecule, leading to extensive hydrogen bonding.
Q43. The hybridisation of boron atom in BF₃ molecule is
(a) sp
(b) sp²
(c) sp³
(d) dsp²
Answer: (b)
Explanation: Boron forms three σ bonds with fluorine atoms and has no lone pair, resulting in sp² hybridisation and trigonal planar geometry.
Q44. The molecular shape of XeF₄ is
(a) Tetrahedral
(b) Square planar
(c) Trigonal bipyramidal
(d) Octahedral
Answer: (b)
Explanation: XeF₄ has four bond pairs and two lone pairs arranged opposite each other, giving a square planar shape.
Q45. Which of the following detergents is biodegradable?
(a) Branched-chain detergents
(b) Phosphate detergents
(c) Straight-chain detergents
(d) Cationic detergents
Answer: (c)
Explanation: Straight-chain detergents are easily decomposed by microorganisms and hence are environmentally friendly.
Q46. Aldol reaction is shown by aldehydes and ketones which
(a) Are aromatic
(b) Are unsaturated
(c) Contain α-hydrogen
(d) Are acidic
Answer: (c)
Explanation: Presence of α-hydrogen is essential for enolate ion formation, which initiates aldol reaction.
Q47. The most suitable method for preparation of primary amines is
(a) Hoffmann bromamide reaction
(b) Gabriel phthalimide synthesis
(c) Reduction of nitro compounds
(d) Ammonolysis of alkyl halides
Answer: (b)
Explanation: Gabriel synthesis selectively forms primary amines without producing secondary or tertiary amines.
Q48. Electrical conductance of an electrolyte solution increases with
(a) Increase in pressure
(b) Decrease in temperature
(c) Increase in temperature
(d) Decrease in concentration
Answer: (c)
Explanation: Increase in temperature enhances ionic mobility, leading to higher electrical conductance.
Q49. Glucose can be identified by
(a) Fehling’s test only
(b) Tollens’ test only
(c) Benedict’s test only
(d) Both Fehling’s and Tollens’ tests
Answer: (d)
Explanation: Glucose is a reducing sugar and gives positive results with both Fehling’s and Tollens’ reagents.
Q50. CBSE Class 12 Chemistry board examinations primarily focus on
(a) Rote memorisation
(b) Advanced numerical problems
(c) Research-level chemistry
(d) NCERT concepts and applications
Answer: (d)
Explanation: CBSE strictly follows NCERT and tests conceptual clarity, trends, reactions, and real-life applications.
✅ Ultra-Frequently Asked Section Completed
- Covers sure-shot board facts
- Ideal for last-day revision
- Fully NCERT aligned
- High probability of direct exam questions