CBSE Class 12 Chemistry Previous Year Question Paper and Solutions: A Guide

Layout of a class 12 chemistry previous year question paper

Recent board papers (from the 2024 and 2025 exams) and the current sample paper use this layout:

Older papers, from before the NCERT rationalisation, include solid state, surface chemistry, p block and polymers. Leave those out, since none of them belongs to the current chemistry class 12 syllabus.

What past chemistry papers keep asking

Lay the last few board papers next to each other and certain question types jump out:

• Physical numericals: molar mass from a colligative property, EMF or equilibrium constant from the Nernst equation, molar conductivity and Kohlrausch's law, rate constant and half life of a first order reaction.
• Coordination compounds: IUPAC names, hybridisation and magnetic behaviour, crystal field splitting, and isomers of a given complex.
• d and f block reasoning: "give reasons" items on oxidation states, colour, magnetic moment and lanthanoid contraction.
• Organic reactions: named reactions (Cannizzaro, aldol, Hofmann bromamide, Gabriel phthalimide, Sandmeyer, Reimer Tiemann, Clemmensen, Wolff Kishner), two or three step conversions, and tests to tell two compounds apart.
• Biomolecules: structure and reactions of glucose, types of protein structure, vitamins and their deficiency, DNA versus RNA.

The case based questions in section D usually take a short passage or data table from one chapter, often kinetics, electrochemistry or biomolecules, and ask three or four linked questions.

How to use the official marking scheme

The CBSE marking scheme is the real "solution". It shows the expected answer in points and how many marks each step earns. Use it like an examiner:

1. Solve the paper first without looking at anything.
2. Check each answer against the scheme and give yourself marks only for the points written there.
3. Notice where marks are split: a formula, the substitution, the final value with unit. Students lose marks on missing units far more than on wrong arithmetic.
4. Copy the exact wording of definitions and reasons from the scheme into your notes.

A practice plan for the last two months

• Weeks 1 to 3: chapter wise. After finishing a chapter, collect its questions from five past papers and attempt the whole batch at a stretch.
• Weeks 4 to 6: two full papers a week, timed at three hours, checked with the marking scheme.
• Final two weeks: the latest sample paper, then the newest board papers from other regions, and a final run through your reactions sheet. NEET aspirants can add a few NEET previous papers for MCQ speed.
• Other subjects: the CBSE class 12 syllabus page helps you balance chemistry with the rest.

Try these: five original chemistry items

Five items we composed for this page; they mirror recent formats without copying any board question.

1. (1 mark) Which of these aqueous solutions has the highest boiling point? (a) 0.1 M glucose (b) 0.1 M NaCl (c) 0.1 M CaCl2 (d) 0.1 M urea
2. (2 marks) A first order reaction is 50% complete in 30 minutes. How long will it take to be 75% complete? Explain briefly.
3. (3 marks) Write the IUPAC name of [Co(NH3)5Cl]Cl2, state the oxidation state of cobalt, and say whether the complex shows geometrical isomerism.
4. (3 marks) How will you convert benzene diazonium chloride into (i) phenol (ii) chlorobenzene (iii) iodobenzene?
5. (Assertion and reason) Assertion: Phenol is more acidic than ethanol. Reason: The negative charge of the phenoxide ion spreads over the benzene ring.

Short answers: 1 (c), because CaCl2 gives three ions. 2: 60 minutes, as two half lives are needed. 3: pentaamminechloridocobalt(III) chloride; cobalt is +3; no geometrical isomerism, since only one chloride sits in the coordination sphere with five identical ammine ligands. 4: (i) warm with water (ii) CuCl with HCl, the Sandmeyer reaction (iii) KI. 5: both statements are true, and the reason correctly explains the assertion, because this delocalisation steadies the phenoxide ion.

Where to get the chemistry class 12 previous year question paper officially

CBSE is the only source you need:

• Main website: the board's site at cbse.gov.in carries past question papers and, separately, the marking schemes, arranged by year and subject.
• Academic website: cbseacademic.nic.in is where the board places each session's model chemistry paper, its answer points and the curriculum file.

Each year has several sets (for example for Delhi, outside Delhi and foreign centres). Solve more than one set of the same year; they test the same syllabus with different questions, which gives you extra practice at the right level. For other subjects, see CBSE class 12 previous papers.

Mistakes that cost marks in past papers

• Writing a reaction without conditions or a reagent over the arrow.
• Leaving out units or significant figures in numericals.
• Drawing structures of glucose or complexes without labels.
• Answering "give reasons" with a fact instead of the cause.
• Spending 20 minutes on a one mark question that you could have skipped and returned to.

Track which of these you make while checking each paper, and the habit fades within a few attempts.