Which Chemistry chapters are most important for Class 12?

By marks: Organic Chemistry (haloalkanes to biomolecules) carries ~19 marks, Inorganic (p-block, d-block, coordination) carries ~28 marks, Physical Chemistry (solutions, electrochemistry, kinetics) carries ~23 marks. Inorganic has the most marks but is mostly NCERT memorisation. Physical Chemistry numericals are the most scoring.

How to score 90+ in Chemistry board exam?

Branch-wise approach: (1) Inorganic: read NCERT 3 times, memorise every table and exception. (2) Physical: master 15 key formulas, solve 50+ numericals. (3) Organic: learn all named reactions, practise conversions daily. Chemistry is 70% memory (Inorganic + Organic reactions) and 30% problem-solving (Physical).

Is NCERT enough for Chemistry boards?

Yes — 95%+ of board Chemistry questions are from NCERT. For Inorganic, NCERT is the ONLY source. For Physical, NCERT examples cover all numerical types. For Organic, NCERT named reactions and mechanisms are sufficient. Reference books are for JEE/NEET, not boards.

How many named reactions are asked in Chemistry?

Typically 3-5 named reactions are asked directly or as part of conversions, carrying 6-10 marks total. Must-know: Sandmeyer, Kolbe, Reimer-Tiemann, Williamson, Aldol, Cannizzaro, Hofmann bromamide, Gabriel phthalimide, Wurtz, Friedel-Crafts. Write reaction + reagent + condition for full marks.

Chemistry Important Questions Class 12 — 2026

CBSE Class 12 Chemistry: 70 marks theory + 30 marks practical. Inorganic Chemistry carries the most marks (~28) and is purely NCERT-based. Physical Chemistry (~23 marks) is numerical-heavy and scoring. Organic Chemistry (~19 marks) needs reaction mastery. Below are the most expected questions from each branch.

Branch-Wise Marks Split

Branch	Chapters	Marks
Physical Chemistry	Solid State, Solutions, Electrochemistry, Kinetics, Surface Chemistry	~23
Inorganic Chemistry	p-Block, d & f Block, Coordination Compounds, Metallurgy	~28
Organic Chemistry	Haloalkanes, Alcohols, Aldehydes, Amines, Biomolecules, Polymers	~19

Physical Chemistry

Solutions

Question	Marks
State Raoult's law. Explain positive and negative deviations with examples and graphs.	5
Calculate the boiling point elevation when 1.5g of a non-volatile solute (M = 60) is dissolved in 100g of water (Kb = 0.52 K kg/mol).	3
What are colligative properties? Name all four. Why does addition of solute lower vapour pressure?	3
Calculate the osmotic pressure of a 0.1M glucose solution at 27°C (R = 0.0821 L atm/mol K).	2
What is van't Hoff factor? How is it related to degree of dissociation?	3

Electrochemistry

Question	Marks
State and explain Nernst equation. Calculate the EMF of a cell: Zn\|Zn²⁺(0.1M)\|\|Cu²⁺(0.01M)\|Cu (E° = 1.10V).	5
What is molar conductivity? How does it vary with concentration for strong and weak electrolytes? Draw graph.	5
State Faraday's first and second laws of electrolysis. Calculate the mass of copper deposited by 0.5A current in 1 hour.	3
Explain the working of a hydrogen fuel cell with diagram.	3
What are primary and secondary cells? Give one example of each.	2

Chemical Kinetics

Question	Marks
Derive the integrated rate equation for a first-order reaction: k = (2.303/t)log(a/(a−x)).	5
A first-order reaction has k = 1.15×10⁻³ s⁻¹. Find t½ and the time for 90% completion.	3
Define: (a) order of reaction, (b) molecularity. How do they differ?	3
Using Arrhenius equation, explain the effect of temperature on reaction rate. What is activation energy?	3

Solid State

Question	Marks
Describe the three types of cubic unit cells (simple, BCC, FCC). Calculate packing efficiency for each.	5
Calculate the density of a substance with FCC structure: a = 400pm, M = 60 g/mol.	3
What are Schottky and Frenkel defects? Which type of ionic compound shows which defect?	3

Chemistry chapter-wise practice

Super Tutor has Physical, Organic, and Inorganic Chemistry questions for Class 12 — numericals, reactions, and NCERT-based theory.

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Inorganic Chemistry

p-Block Elements

Question	Marks
Give reasons: (a) Nitrogen is a gas but phosphorus is a solid. (b) Bi is a strong oxidising agent in +5 state. (c) Noble gases have very low boiling points.	3
What happens when: (a) SO₂ is passed through acidified KMnO₄, (b) Cl₂ is passed through NaOH (cold and hot)?	3
Draw the structures of: (a) XeF₂, (b) XeF₄, (c) H₂SO₄, (d) PCl₅, (e) H₃PO₄.	3
Describe the preparation of: (a) sulphuric acid by Contact process, (b) nitric acid by Ostwald process.	5
What are interhalogen compounds? Give 4 examples. Why are they more reactive than halogens?	3
Explain the anomalous behaviour of nitrogen compared to other Group 15 elements.	3

d & f Block Elements

Question	Marks
Why are transition elements coloured? Which d-block element is not coloured and why?	3
Give reasons: (a) Zn is not a transition element. (b) Cr has [Ar]3d⁵4s¹. (c) Transition metals show variable oxidation states.	3
What are lanthanoid contraction? What are its consequences?	3
Describe the preparation and properties of: (a) KMnO₄, (b) K₂Cr₂O₇.	5
Calculate the magnetic moment of Fe²⁺ (atomic number 26).	2

Coordination Compounds

Question	Marks
Write the IUPAC name of: [Co(NH₃)₅Cl]Cl₂, K₃[Fe(CN)₆], [Pt(NH₃)₂Cl₂], [CoCl₂(en)₂]⁺	2–3
Explain crystal field theory (CFT) for octahedral complexes. What is crystal field splitting energy (Δo)?	5
What is geometrical isomerism? Draw cis and trans isomers of [Pt(NH₃)₂Cl₂].	3
What is the spectrochemical series? How does it explain colour of complexes?	3

Organic Chemistry

Haloalkanes & Haloarenes

Question	Marks
Explain SN1 and SN2 mechanisms with examples. Which is faster for: (a) primary halide, (b) tertiary halide?	5
Give reasons: (a) C−Cl bond in chlorobenzene is shorter than in chloroethane. (b) Vinyl chloride does not undergo SN reactions easily.	3
Convert: (a) chlorobenzene to biphenyl, (b) 2-bromopropane to 1-bromopropane.	3

Alcohols, Phenols & Ethers

Question	Marks
How would you distinguish between: (a) 1°, 2°, 3° alcohols (Lucas test), (b) methanol and ethanol, (c) phenol and ethanol?	5
Explain Kolbe's reaction and Reimer-Tiemann reaction with equations.	3
Explain Williamson ether synthesis. Why is it better for preparing mixed ethers?	3

Aldehydes, Ketones & Carboxylic Acids

Question	Marks
Explain Aldol condensation and Cannizzaro reaction with examples.	5
How will you distinguish between: (a) aldehyde and ketone (Tollens' test, Fehling's test), (b) formic acid and acetic acid?	3
Arrange in increasing order of reactivity towards nucleophilic addition: HCHO, CH₃CHO, (CH₃)₂CO. Give reason.	3
Convert: (a) benzaldehyde to benzoin, (b) ethanal to 3-hydroxybutanal, (c) benzoic acid to benzaldehyde.	3

Amines

Question	Marks
Explain Hofmann bromamide degradation and Gabriel phthalimide synthesis with equations.	5
Arrange in increasing order of basic strength: aniline, methylamine, dimethylamine, ammonia. Explain.	3
What is diazotisation? Write 3 reactions of diazonium salt (Sandmeyer reactions).	3
Why is aniline less basic than methylamine?	2

Biomolecules & Polymers

Question	Marks
What are reducing and non-reducing sugars? Give one example each. How do you test for reducing sugar?	3
Differentiate between: (a) DNA and RNA, (b) starch and cellulose, (c) globular and fibrous proteins.	3
What are addition and condensation polymers? Give 2 examples of each with their monomers.	3
What are biodegradable polymers? Give 2 examples. Why are they important?	2

Questions based on analysis of CBSE Class 12 Chemistry papers (2018–2025) and 2026 sample paper. Marks from CBSE 2025–2026 blueprint. Complete NCERT thoroughly before using this as a revision guide. Last updated: February 2026.

Chemistry Important Questions Class 12 CBSE 2026 — Chapter Wise