CBSE Class 12 Chemistry Sample Paper Set 2 — Free PDF
Comprehensive chemistry sample paper covering organic, inorganic, and physical chemistry topics. Master reactions, mechanisms, and calculations with detail
TL;DR: Comprehensive chemistry sample paper covering organic, inorganic, and physical chemistry topics. Master reactions, mechanisms, and calculations with d…
Written & reviewed by the Syllab.in Academic Team (CBSE/NCERT subject experts) · Updated
Comprehensive chemistry sample paper covering organic, inorganic, and physical chemistry topics. Master reactions, mechanisms, and calculations with detailed solutions for Class 12 board exams. This is a shortened practice set: 27 questions worth 69 marks, following the 70-mark CBSE paper pattern. Use it for timed practice, not as a full-length mock.
Board: CBSE · Class: Class 12 · Subject: Chemistry · Total: 69 marks · Time: 3 hours
Section A - Objective Type Questions — 8 marks
Attempt all questions. Each question carries 1 mark.
Q1. The value of Avogadro's number is? (1 mark)
Answer: 6.022 x 10^23
Q2. Which element has highest electronegativity? (1 mark)
Answer: Fluorine
Q3. The SI unit of pressure is? (1 mark)
Answer: Pascal (Pa)
Q4. What is the oxidation state of sulfur in H2SO4? (1 mark)
Answer: +6
Q5. The pH of neutral solution is? (1 mark)
Answer: 7
Q6. Which gas is used in making ammonia by Haber process? (1 mark)
Answer: Nitrogen and Hydrogen
Q7. What is the general formula for alkanes? (1 mark)
Answer: CnH2n+2
Q8. The catalyst used in contact process is? (1 mark)
Answer: Vanadium pentoxide (V2O5)
Section B - Short Answer Questions — 28 marks
Attempt all questions. Each question carries 2 or 3 marks.
Q1. What is Mohs scale? Give its uses. (2 marks)
Answer: Measures hardness of minerals from 1 (softest) to 10 (hardest), Used to identify minerals
Q2. Explain Le Chatliers principle with example. (3 marks)
Answer: System shifts to counteract change, Example: N2 + 3H2 <-> 2NH3, Increase pressure shifts right
Q3. What is buffer solution? How does it resist pH change? (2 marks)
Answer: Weak acid + its salt or weak base + its salt, Neutralizes added acid or base, Maintains constant pH
Q4. Write the electronic configuration of transition metals and explain d-block elements. (3 marks)
Answer: Configuration: (n-1)d^1-10 ns^1-2, Partially filled d orbitals, Show variable oxidation states
Q5. Explain the concept of hybridization with example. (2 marks)
Answer: Mixing of atomic orbitals, Example: Carbon in CH4 is sp^3 hybridized
Q6. What is isomerism? Explain structural and stereoisomerism. (3 marks)
Answer: Same molecular formula different structure, Structural: chain, position, functional group isomers, Stereoisomerism: geometric and optical
Q7. Describe the mechanism of SN1 reaction with example. (2 marks)
Answer: Unimolecular nucleophilic substitution, Two-step: carbocation formation then nucleophile attack
Q8. What is Friedel-Crafts alkylation? Write its conditions. (2 marks)
Answer: Introduction of alkyl group in benzene, Requires AlCl3 catalyst and alkyl halide
Q9. Explain polymer formation and classification of polymers. (3 marks)
Answer: Long chain of repeating units, Natural: protein, cellulose; Synthetic: polyethylene, polyester
Q10. What is saponification? Write equation for soap formation. (2 marks)
Answer: Hydrolysis of fat by NaOH, Fat + NaOH -> Glycerol + Fatty acid salt (soap)
Q11. Define Gibbs free energy and write its expression. (2 marks)
Answer: G = H - TS, Determines spontaneity of reaction, Delta-G < 0 for spontaneous process
Q12. Explain primary, secondary, and tertiary amines with examples. (2 marks)
Answer: Primary: RNH2, Secondary: R2NH, Tertiary: R3N, Differ by number of alkyl groups
Section C - Long Answer Questions — 33 marks
Attempt all questions. Each question carries 4 or 5 marks.
Q1. Explain the preparation of ammonia by Haber process with conditions and industrial importance. (5 marks)
Answer: N2 + 3H2 <-> 2NH3, Conditions: 400-500C, 150-200 atm pressure, Iron catalyst, Used for fertilizers and explosives
Q2. Derive thermodynamic expression for electrode potential. Explain Nernst equation. (5 marks)
Answer: E = E0 - (RT/nF)ln(Q), Relates cell potential to concentrations and temperature
Q3. Explain the preparation and properties of benzene. Discuss its aromaticity. (5 marks)
Answer: Prepared by decarboxylation of benzoic acid or reduction of phenol, Resonance stabilization, Exceptional stability, Prefers substitution over addition
Q4. Describe the mechanism of free radical substitution in alkanes with example. (5 marks)
Answer: Initiation: generation of free radicals, Propagation: radical chain reactions, Termination: combination of radicals, Example: Chlorination of methane
Q5. Explain qualitative analysis scheme for cations. Discuss Group I, II, III, IV, V precipitations. (5 marks)
Answer: Group I: Pb2+, Ag+, Hg2+ with HCl, Group II: Hg2+, Pb2+, Bi3+ with H2S, Systematic identification based on solubility
Q6. Write a detailed note on carbohydrates. Classify and explain monosaccharides and polysaccharides. (4 marks)
Answer: Polyhydroxy aldehydes or ketones, Monosaccharides: glucose, fructose; Disaccharides: sucrose, maltose; Polysaccharides: starch, glycogen
Q7. Discuss factors affecting rate of reaction with Arrhenius equation explanation. (4 marks)
Answer: Temperature, Concentration, Pressure, Catalyst, Surface area, k = A*e^(-Ea/RT), Lower activation energy increases rate
FAQs
What is the exam pattern for Class 12 Chemistry?
70 marks with 3 hours duration, covering sections on physical, inorganic, and organic chemistry with MCQ, short answer, and long answer questions.
Which topics are most frequently asked?
Chemical reactions, Thermodynamics, Electrochemistry, Organic mechanisms, Polymers, and Qualitative analysis are important topics.
How to prepare for reactions and mechanisms?
Practice writing equations, understand reaction mechanisms step by step, learn reaction conditions, and practice various problem types regularly.
All sample papers → · Previous-year questions → · Chapter-wise MCQs →