Important Questions Chemistry Class 12 2025-26 PDF with Solution

Chemistry is not just a subject; it is the story of how matter behaves and changes. In Class 12, it becomes more conceptual and applied, forming the base for higher studies in science, medicine, and engineering. 

This guide gives you detailed, chapter-wise important questions and explanations based on the latest CBSE pattern, along with practical advice on how to study and write answers the way examiners expect. Here's how this blog might help you:

• Study one chapter at a time. Read concepts first, then attempt questions.
• Note key formulas and named reactions separately.
• Revise from the FAQs and final tips before exams for last-minute confidence.

CBSE Most Important Questions For Class 12 Chemistry

In the table given below, we have provided the links to downloadable PDFs of chapter-wise important questions for class 12 Chemistry and that too for different categories of marks.

CBSE CLASS 12 CHEMISTRY IMPORTANT QUESTIONS

Q1. What is the difference between crystalline and amorphous solids?

Ans. Crystalline solids have a regular and repeating arrangement of particles, sharp melting points, and definite geometrical shapes (example: NaCl, quartz). Amorphous solids have irregular particle arrangement, no sharp melting point, and behave more like super-cooled liquids (example: glass, rubber).

Q2. State Raoult’s Law for a solution of volatile liquids.

Ans. Raoult’s Law states that the partial vapour pressure of each component in a solution is directly proportional to its mole fraction. Total vapour pressure is obtained by adding the partial pressures of the components. The law works best for ideal solutions.

Q3. What is the difference between electrolytic and galvanic cells?

Ans.  Galvanic cells convert chemical energy to electrical energy spontaneously, while electrolytic cells require an external source of electricity to bring about a chemical reaction. In galvanic cells, oxidation occurs at the anode and reduction at the cathode; in electrolytic cells, the polarity is reversed because current is forced.

Q4. Define Kohlrausch’s Law.

Ans. Kohlrausch’s Law states that at infinite dilution, the molar conductivity of an electrolyte is equal to the sum of the individual contributions of its ions. It is used to calculate molar conductivity of weak electrolytes.

Q5. What is the order of a reaction?

Ans. Order is the sum of the powers of the concentration terms in the rate law. It is determined experimentally and may be zero, fractional, or whole. Example: For rate = k[A]^2[B], order = 3.

Q6. Explain the effect of temperature on rate of reaction.

Ans. Rate increases with temperature because a higher fraction of molecules attain activation energy. According to the Arrhenius equation, rate constant increases exponentially with temperature, showing sensitivity of reactions to heat.

Q7. What is adsorption? Give one example.

Ans. Adsorption is the accumulation of molecules on the surface of a solid or liquid. Example: charcoal adsorbing gases like ammonia or nitrogen.

Q8. Why do transition metals form coloured compounds?

Ans. Transition metals have partially filled d orbitals. When light falls on them, electrons transition between d orbitals, producing characteristic colours.

Q9. Why do transition metals act as good catalysts?

Ans. They can change oxidation states easily and provide active surfaces for reactions. Adsorption of reactants on these surfaces lowers activation energy.

Q10. What is Werner’s theory?

Ans. Werner proposed that metal ions exhibit two types of valencies: primary valency (ionisable) and secondary valency (non-ionisable). Secondary valency determines the geometry of the complex.

Q11. What is the difference between a ligand and a coordination number?

Ans. A ligand donates a pair of electrons to the central metal ion. Coordination number refers to the number of ligand donor atoms attached to the metal.

Q12. Why do haloalkanes undergo nucleophilic substitution easily?

Ans.  Carbon halogen bonds are polar because halogens are electronegative. This creates a partial positive charge on carbon, making it vulnerable to nucleophilic attack.

Q13. Why is phenol more acidic than alcohol?

Ans. Phenoxide ion formed after losing H+ is stabilised by resonance, which alcohols lack. This stabilization increases acidic strength of phenol.

Q14. What is the mechanism of nucleophilic addition in aldehydes?

Ans. The carbonyl carbon is partially positive due to C=O polarity. Nucleophile attacks this carbon, resulting in breaking of the pi bond. Protonation follows, giving additional products.

Q15. What is the Hoffmann bromamide degradation reaction?

Ans. In this reaction, amides react with bromine in the presence of base to form amines with one carbon less. It is useful for shortening carbon chains.

Q16. What are reducing sugars? Give examples.

Ans. Reducing sugars contain free aldehyde or keto groups capable of reducing reagents. Examples: glucose, fructose, maltose.

Q17. What is denaturation of proteins?

Ans. Denaturation is the loss of secondary and tertiary structure due to heat, acids, or chemicals. The primary structure remains intact. Example: curdling of milk.

Q18. What is the difference between addition and condensation polymers?

Ans. Addition polymers form by repeated addition of monomers without loss of molecules (example: polyethylene). Condensation polymers form by combining monomers with elimination of small molecules like water (example: nylon-6,6).

Q19. What are analgesics?

Ans. Analgesics are drugs that reduce pain without causing unconsciousness.
Examples include aspirin and paracetamol.

Q20. What are food preservatives?

Ans. Food preservatives prevent spoilage by inhibiting microbial growth. Common examples include sodium benzoate and salts of sorbic acid.

EXTRA QUESTIONS FOR PRACTICE 

Q1. State and explain Henry’s Law. Mention its two important applications.

Q2. Define the term molar conductivity. How does it vary with concentration for strong and weak electrolytes?

Q3. Derive the integrated rate equation for a first-order reaction.

Q4. Write the general electronic configuration of d-block elements. Why do they form colored compounds?

Q5. Explain the crystal field splitting in an octahedral complex with a labeled diagram.

Q6. Distinguish between SN1 and SN2 reactions with suitable examples.

Q7. Write short notes on (a) Cannizzaro reaction (b) Hoffmann bromamide reaction.

Q8. Define biomolecules. Classify carbohydrates and give one example of each type.

Q9. Explain the preparation and properties of ethanoic acid.

Q10. What are lanthanoids? Mention two characteristic properties of lanthanoids.

Why You Should Definitely Practise These Class 12 Chemistry Important Questions

Before you start solving, here’s why these Class 12 Chemistry important questions are a total game-changer for your board prep:

• You’ll easily spot commonly asked CBSE question patterns and get used to the paper style.
• They help you strengthen your concepts across Physical, Organic, and Inorganic Chemistry.
• You’ll get better at numericals, especially from tricky chapters like Electrochemistry, Kinetics, and Solutions.
• Derivations and mechanisms start feeling easier once you see them repeatedly in questions.
• They help you figure out weak areas so you know what to revise again.
• You’ll learn how to present your answers neatly - with proper equations, reactions, and stepwise logic.
• Solving them boosts your exam confidence, since you’re practising real board-style difficulty.
• It helps you save time by focusing your energy on the most important, high-weightage topics.
• You’ll learn to connect ideas across chapters, which really helps in competency-based questions.
• And most importantly, you’ll feel less exam stress - because you’ll recognise most question types instantly.

Tips to Use These Class 12 Chemistry Important Questions Like a Pro

Here’s how to make your Class 12 Chemistry important questions practice actually work for you (and not feel like endless revision):

• Revise NCERT first - trust me, most Chemistry board questions are straight from there.
• Keep a reaction notebook for all named reactions, reagents, and conditions - it’ll save you tons of time before Organic Chemistry practice.
• For Physical Chemistry, write down all formulas separately and show every step in numericals.
• When practising mechanisms, draw every arrow and step clearly - CBSE really values neatness here.
• For Inorganic Chemistry, make short notes on colour changes, magnetic properties, and coordination numbers - they’re almost always asked.
• Use a timer when solving 3-mark or 5-mark questions to build real exam speed.
• After each chapter, redo the questions you got wrong - without peeking at the answers this time.
• Keep a “tough questions” list handy and revisit it just before exams.
• Compare your work with official marking-scheme style answers to get a feel for ideal length and tone.
• And finally, before boards, mix up questions from all chapters to test your full-syllabus grip and lift confidence.