Practice Question Papers · with Answers

CBSE / NCERT Class 12 Chemistry Practice Question Papers

Download free CBSE / NCERT Class 12 Chemistry practice question papers with full answer keys. These are original Brain Grain model papers — built from our verified question bank to the real exam blueprint (sections, marks and solutions) — perfect for board revision and model tests. For the actual board papers, use the official links below.

Brain Grain · braingrain.in
Chemistry — Practice Paper · Set 1
Class: 12CBSE / NCERTMax Marks: 32
Name: ____________________Reg No: ____________
Part I — Multiple Choice Questions 4 × 1 = 4

Choose the correct answer. (Answer all questions.)

1.Amongst the following, the most stable complex is (i) [Fe(H2O)6]3+ (ii) [Fe(NH3)6]3+ (iii) [Fe(C2O4)3]3– (iv) [FeCl6]3–i. [Fe(H2O)6]3+ii. [Fe(NH3)6]3+iii. [Fe(C2O4)3]3-iv. [FeCl6]3-[1]
2.Which one of the following has the highest dipole moment? (i) CH2Cl2 (ii) CHCl3(iii) CCl4i. CH2Cl2ii. CHCl3iii. CCl4[1]
3.Amongst the following ions which one has the highest magnetic moment value? (i) [Cr(H2O)6]3+ (ii) [Fe(H2O)6]2+ (iii) [Zn(H2O)6]2+i. [Cr(H2O)6]3+ii. [Fe(H2O)6]2+iii. [Zn(H2O)6]2+[1]
4.What will be the correct order for the wavelengths of absorption in the visible region for the following: [Ni(NO2)6]4–, [Ni(NH3)6]2+, [Ni(H2O)6]2+ ?i. [Ni(NO2)6]4- > [Ni(NH3)6]2+ > [Ni(H2O)6]2+ii. [Ni(H2O)6]2+ > [Ni(NH3)6]2+ > [Ni(NO2)6]4-iii. [Ni(NH3)6]2+ > [Ni(H2O)6]2+ > [Ni(NO2)6]4-[1]
Part II — Short Answer Questions 14 × 2 = 28

Answer briefly. (Answer all questions.)

5.Give one chemical test to distinguish between the following pairs of compounds. (i) Methylamine and dimethylamine (ii) Secondary and tertiary amines (iii) Ethylamine and aniline (iv) Aniline and benzylamine (v) Aniline and N-methylaniline.[2]
6.Why are vitamin A and vitamin C essential to us? Give their important sources.[2]
7.Comment on the statement that elements of the first transition series possess many properties different from those of heavier transition elements.[2]
8.Suggest the most important type of intermolecular attractive interaction in the following pairs. (i) n-hexane and n-octane (ii) I2 and CCl4 (iii) NaClO4 and water (iv) methanol and acetone (v) acetonitrile (CH3CN) and acetone (C3H6O).[2]
9.What type of bonding helps in stabilising the a-helix structure of proteins?[2]
10.How do you explain the amphoteric behaviour of amino acids?[2]
11.Discuss briefly giving an example in each case the role of coordination compounds in: (i) biological systems (iii) analytical chemistry (ii) medicinal chemistry and (iv) extraction/metallurgy of metals.[2]
12.Name the reagents used in the following reactions: (i) Oxidation of a primary alcohol to carboxylic acid. (ii) Oxidation of a primary alcohol to aldehyde. (iii) Bromination of phenol to 2,4,6-tribromophenol. (iv) Benzyl alcohol to benzoic acid. (v) Dehydration of propan-2-ol to propene. (vi) Butan-2-one to butan-2-ol.[2]
13.Preparation of ethers by acid dehydration of secondary or tertiary alcohols is not a suitable method. Give reason.[2]
14.What are the hydrolysis products of (i) sucrose and (ii) lactose?[2]
15.Determine the osmotic pressure of a solution prepared by dissolving 25 mg of K2SO4 in 2 litre of water at 25 °C, assuming that it is completely dissociated.[2]
16.Write the mechanism of the reaction of HI with methoxymethane.[2]
17.What are reducing sugars?[2]
18.How are the following conversions carried out? (i) Propene ® Propan-2-ol. (ii) Benzyl chloride ® Benzyl alcohol. (iii) Ethyl magnesium chloride ® Propan-1-ol. (iv) Methyl magnesium bromide ® 2-Methylpropan-2-ol.[2]
🔑 Show Answer Key — Set 1
  1. 1. (iii) [Fe(C2O4)3]3-.
  2. 2. (i) CH2Cl2.
  3. 3. (ii) [Fe(H2O)6]2+.
  4. 4. [Ni(H2O)6]2+ > [Ni(NH3)6]2+ > [Ni(NO2)6]4-.
  5. 5. Use carbylamine, Hinsberg and nitrous acid/diazotisation tests depending on the pair.
  6. 6. Vitamin A is needed for healthy eyes and vision; vitamin C prevents scurvy and supports healthy gums/tissues. Vitamin A sources include fish liver oil, carrots, butter and milk; vitamin C sources include citrus fruits, amla and green leafy vegetables.
  7. 7. The first transition series differs because 3d orbitals are smaller and less diffuse than 4d and 5d orbitals.
  8. 8. (i) London dispersion; (ii) London dispersion; (iii) ion-dipole; (iv) hydrogen bonding/dipole-dipole; (v) dipole-dipole.
  9. 9. Hydrogen bonding stabilises the alpha-helix structure.
  10. 10. Amino acids are amphoteric because they contain both acidic –COOH and basic –NH2 groups and exist as zwitterions.
  11. 11. Coordination compounds are important in biological systems, medicine, analysis and metallurgy.
  12. 12. (i) Acidified KMnO4 or K2Cr2O7. (ii) PCC or controlled oxidation. (iii) Bromine water. (iv) Acidified KMnO4. (v) Conc. H2SO4, heat. (vi) NaBH4 or LiAlH4.
  13. 13. Secondary and tertiary alcohols undergo elimination more readily than substitution under acid dehydration conditions.
  14. 14. (i) Sucrose gives glucose and fructose. (ii) Lactose gives galactose and glucose.
  15. 15. 5.26 x 10^-3 atm.
  16. 16. Methoxymethane is protonated and then iodide attacks a methyl group by SN2 to give methanol and methyl iodide; excess HI converts methanol to methyl iodide.
  17. 17. Reducing sugars are carbohydrates that reduce Fehling's solution and Tollens' reagent.
  18. 18. (i) Acid-catalysed hydration. (ii) Hydrolysis with aqueous alkali. (iii) Reaction with formaldehyde followed by hydrolysis. (iv) Reaction with acetone followed by hydrolysis.
Brain Grain · braingrain.in
Chemistry — Practice Paper · Set 2
Class: 12CBSE / NCERTMax Marks: 32
Name: ____________________Reg No: ____________
Part I — Multiple Choice Questions 4 × 1 = 4

Choose the correct answer. (Answer all questions.)

1.What will be the correct order for the wavelengths of absorption in the visible region for the following: [Ni(NO2)6]4–, [Ni(NH3)6]2+, [Ni(H2O)6]2+ ?i. [Ni(NO2)6]4- > [Ni(NH3)6]2+ > [Ni(H2O)6]2+ii. [Ni(H2O)6]2+ > [Ni(NH3)6]2+ > [Ni(NO2)6]4-iii. [Ni(NH3)6]2+ > [Ni(H2O)6]2+ > [Ni(NO2)6]4-[1]
2.Amongst the following, the most stable complex is (i) [Fe(H2O)6]3+ (ii) [Fe(NH3)6]3+ (iii) [Fe(C2O4)3]3– (iv) [FeCl6]3–i. [Fe(H2O)6]3+ii. [Fe(NH3)6]3+iii. [Fe(C2O4)3]3-iv. [FeCl6]3-[1]
3.Which one of the following has the highest dipole moment? (i) CH2Cl2 (ii) CHCl3(iii) CCl4i. CH2Cl2ii. CHCl3iii. CCl4[1]
4.Amongst the following ions which one has the highest magnetic moment value? (i) [Cr(H2O)6]3+ (ii) [Fe(H2O)6]2+ (iii) [Zn(H2O)6]2+i. [Cr(H2O)6]3+ii. [Fe(H2O)6]2+iii. [Zn(H2O)6]2+[1]
Part II — Short Answer Questions 14 × 2 = 28

Answer briefly. (Answer all questions.)

5.Give two reactions that show the acidic nature of phenol. Compare acidity of phenol with that of ethanol.[2]
6.Explain the following with an example. (i) Kolbe’s reaction. (ii) Reimer-Tiemann reaction. (iii) Williamson ether synthesis. (iv) Unsymmetrical ether.[2]
7.What are the different oxidation states exhibited by the lanthanoids?[2]
8.Explain why (i) the dipole moment of chlorobenzene is lower than that of cyclohexyl chloride? (ii) alkyl halides, though polar, are immiscible with water? (iii) Grignard reagents should be prepared under anhydrous conditions?[2]
9.The vapour pressure of pure liquids A and B are 450 and 700 mm Hg respectively, at 350 K. Find out the composition of the liquid mixture if total vapour pressure is 600 mm Hg. Also find the composition of the vapour phase.[2]
10.Calculate the number of unpaired electrons in the following gaseous ions: Mn3+, Cr3+, V3+ and Ti3+. Which one of these is the most stable in aqueous solution?[2]
11.A solution of Ni(NO3)2 is electrolysed between platinum electrodes using a current of 5 amperes for 20 minutes. What mass of Ni is deposited at the cathode?[2]
12.How many geometrical isomers are possible in the following coordination entities? (i) [Cr(C2O4)3]3– (ii) [Co(NH3)3Cl3][2]
13.What is the effect of denaturation on the structure of proteins?[2]
14.What are the characteristics of the transition elements and why are they called transition elements? Which of the d-block elements may not be regarded as the transition elements?[2]
15.Write IUPAC names of the following compounds and classify them into primary, secondary and tertiary amines. (i) (CH3)2CHNH2(ii) CH3(CH2)2NH2(iii) CH3NHCH(CH3)2 (iv) (CH3)3CNH2(v) C6H5NHCH3(vi) (CH3CH2)2NCH3 (vii) m–BrC6H4NH2[2]
16.An aromatic compound ‘A’ on treatment with aqueous ammonia and heating forms compound ‘B’ which on heating with Br2 and KOH forms a compound ‘C’ of molecular formula C6H7N. Write the structures and IUPAC names of compounds A, B and C.[2]
17.A first order reaction takes 40 min for 30% decomposition. Calculate t1/2.[2]
18.At 300 K, 36 g of glucose present in a litre of its solution has an osmotic pressure of 4.98 bar. If the osmotic pressure of the solution is 1.52 bars at the same temperature, what would be its concentration?[2]
🔑 Show Answer Key — Set 2
  1. 1. [Ni(H2O)6]2+ > [Ni(NH3)6]2+ > [Ni(NO2)6]4-.
  2. 2. (iii) [Fe(C2O4)3]3-.
  3. 3. (i) CH2Cl2.
  4. 4. (ii) [Fe(H2O)6]2+.
  5. 5. Phenol reacts with sodium metal and sodium hydroxide. Phenol is more acidic than ethanol.
  6. 6. Kolbe's reaction carboxylates sodium phenoxide; Reimer-Tiemann formylates phenol; Williamson synthesis forms ethers from alkoxides and alkyl halides; an unsymmetrical ether has two different groups bonded to oxygen.
  7. 7. The principal oxidation state is +3; some lanthanoids also show +2 or +4.
  8. 8. (i) C-Cl bond in chlorobenzene has partial double-bond character and lower polarity. (ii) Alkyl halides cannot form strong hydrogen bonds with water. (iii) Grignard reagents react rapidly with water.
  9. 9. Liquid phase: xA = 0.40, xB = 0.60. Vapour phase: yA = 0.30, yB = 0.70.
  10. 10. Mn3+: 4; Cr3+: 3; V3+: 2; Ti3+: 1. Cr3+ is the most stable in aqueous solution.
  11. 11. 1.82 g.
  12. 12. (i) No geometrical isomer; (ii) two geometrical isomers, facial and meridional.
  13. 13. Denaturation destroys secondary and tertiary structures, while the primary structure remains intact.
  14. 14. They have partly filled d orbitals in atoms or ions and show variable oxidation states, coloured ions, magnetic behaviour, complex formation and catalytic activity. Group 12 elements Zn, Cd and Hg are generally not true transition elements.
  15. 15. (i) propan-2-amine, primary. (ii) propan-1-amine, primary. (iii) N-methylpropan-2-amine, secondary. (iv) 2-methylpropan-2-amine, primary. (v) N-methylaniline, secondary. (vi) N-ethyl-N-methylethanamine, tertiary. (vii) 3-bromoaniline, primary.
  16. 16. A is benzoic acid, B is benzamide, and C is aniline.
  17. 17. 77.7 min.
  18. 18. 0.061 mol L^-1.
Brain Grain · braingrain.in
Chemistry — Practice Paper · Set 3
Class: 12CBSE / NCERTMax Marks: 32
Name: ____________________Reg No: ____________
Part I — Multiple Choice Questions 4 × 1 = 4

Choose the correct answer. (Answer all questions.)

1.Amongst the following ions which one has the highest magnetic moment value? (i) [Cr(H2O)6]3+ (ii) [Fe(H2O)6]2+ (iii) [Zn(H2O)6]2+i. [Cr(H2O)6]3+ii. [Fe(H2O)6]2+iii. [Zn(H2O)6]2+[1]
2.What will be the correct order for the wavelengths of absorption in the visible region for the following: [Ni(NO2)6]4–, [Ni(NH3)6]2+, [Ni(H2O)6]2+ ?i. [Ni(NO2)6]4- > [Ni(NH3)6]2+ > [Ni(H2O)6]2+ii. [Ni(H2O)6]2+ > [Ni(NH3)6]2+ > [Ni(NO2)6]4-iii. [Ni(NH3)6]2+ > [Ni(H2O)6]2+ > [Ni(NO2)6]4-[1]
3.Amongst the following, the most stable complex is (i) [Fe(H2O)6]3+ (ii) [Fe(NH3)6]3+ (iii) [Fe(C2O4)3]3– (iv) [FeCl6]3–i. [Fe(H2O)6]3+ii. [Fe(NH3)6]3+iii. [Fe(C2O4)3]3-iv. [FeCl6]3-[1]
4.Which one of the following has the highest dipole moment? (i) CH2Cl2 (ii) CHCl3(iii) CCl4i. CH2Cl2ii. CHCl3iii. CCl4[1]
Part II — Short Answer Questions 14 × 2 = 28

Answer briefly. (Answer all questions.)

5.For M2+/M and M3+/M2+ systems the E° values for some metals are as follows: Cr2+/Cr -0.9V Cr3/Cr2+ -0.4 V Mn2+/Mn -1.2V Mn3+/Mn2+ +1.5 V Fe2+/Fe -0.4V Fe3+/Fe2+ +0.8 V Use this data to comment upon: (i) the stability of Fe3+ in acid solution as compared to that of Cr3+ or Mn3+ and (ii) the ease with which iron can be oxidised as compared to a similar process for either chromium or manganese metal.[2]
6.For the reaction: 2A + B → A2B the rate = k[A][B]^2 with k = 2.0 × 10^-6 mol^-2 L^2 s^-1. Calculate the initial rate of the reaction when [A] = 0.1 mol L^-1, [B] = 0.2 mol L^-1. Calculate the rate of reaction after [A] is reduced to 0.06 mol L^-1.[2]
7.Predict the products formed when cyclohexanecarbaldehyde reacts with following reagents. (i) PhMgBr and then H3O + (ii) Tollens’ reagent (iii) Semicarbazide and weak acid (iv) Excess ethanol and acid (v) Zinc amalgam and dilute hydrochloric acid[2]
8.Give the uses of freon 12, DDT, carbon tetrachloride and iodoform.[2]
9.According to Raoult’s law, what is the relative lowering of vapour pressure of a dilute solution containing non-volatile solute equal to?[2]
10.Give the equations of reactions for the preparation of phenol from cumene.[2]
11.Define the following terms : (i) Mole fraction (ii) Molality (iii) Molarity (iv) Mass percentage.[2]
12.The time required for 10% completion of a first order reaction at 298K is equal to that required for its 25% completion at 308K. If the value of A is 4 × 10^10 s^-1. Calculate k at 318K and Ea.[2]
13.Discuss the nature of bonding in the following coordination entities on the basis of valence bond theory: (i) [Fe(CN)6]4– (ii) [FeF6]3– (iii) [Co(C2O4)3]3– (iv) [CoF6]3–[2]
14.Write the important structural and functional differences between DNA and RNA.[2]
15.What is meant by ‘disproportionation’? Give two examples of disproportionation reaction in aqueous solution.[2]
16.Draw the structures of the following compounds. (i) 3-Methylbutanal (ii) p-Nitropropiophenone (iii) p-Methylbenzaldehyde (iv) 4-Methylpent-3-en-2-one (v) 4-Chloropentan-2-one (vi) 3-Bromo-4-phenylpentanoic acid (vii) p,p’-Dihydroxybenzophenone (viii) Hex-2-en-4-ynoic acid[2]
17.The cell in which the following reaction occurs: 2Fe3+(aq) + 2I-(aq) → 2Fe2+(aq) + I2(s) has E°cell = 0.236 V at 298 K. Calculate the standard Gibbs energy and the equilibrium constant of the cell reaction.[2]
18.How will you convert ethanal into the following compounds? (i) Butane-1,3-diol (ii) But-2-enal (iii) But-2-enoic acid[2]
🔑 Show Answer Key — Set 3
  1. 1. (ii) [Fe(H2O)6]2+.
  2. 2. [Ni(H2O)6]2+ > [Ni(NH3)6]2+ > [Ni(NO2)6]4-.
  3. 3. (iii) [Fe(C2O4)3]3-.
  4. 4. (i) CH2Cl2.
  5. 5. (i) Fe3+ is less stable than Cr3+ but more stable than Mn3+ toward reduction to +2. (ii) Iron is oxidised less readily than chromium but more readily than manganese from metal to M2+.
  6. 6. Initial rate = 8.0 x 10^-9 mol L^-1 s^-1; later rate = 3.89 x 10^-9 mol L^-1 s^-1.
  7. 7. (i) C6H11CH(OH)Ph. (ii) cyclohexanecarboxylic acid. (iii) cyclohexanecarbaldehyde semicarbazone. (iv) C6H11CH(OC2H5)2. (v) methylcyclohexane.
  8. 8. Freon-12 is used as refrigerant/aerosol propellant; DDT as insecticide; carbon tetrachloride as solvent/fire extinguisher feedstock though restricted; iodoform as an antiseptic due to liberation of iodine.
  9. 9. It is equal to the mole fraction of the solute.
  10. 10. Cumene is oxidised to cumene hydroperoxide, which on acid hydrolysis gives phenol and acetone.
  11. 11. Mole fraction is moles of a component divided by total moles; molality is moles of solute per kg solvent; molarity is moles of solute per litre solution; mass percentage is mass of component per 100 mass units of solution.
  12. 12. Ea ≈ 76.7 kJ mol^-1; k at 318 K ≈ 1.02 x 10^-2 s^-1.
  13. 13. (i) inner orbital d2sp3, diamagnetic; (ii) outer orbital sp3d2, paramagnetic; (iii) inner orbital d2sp3, diamagnetic; (iv) outer orbital sp3d2, paramagnetic.
  14. 14. DNA contains 2-deoxyribose, thymine and usually a double helix; RNA contains ribose, uracil and is usually single stranded. DNA stores hereditary information, while RNA participates directly in protein synthesis.
  15. 15. Disproportionation is simultaneous oxidation and reduction of the same species.
  16. 16. (i) CH3CH(CH3)CH2CHO. (ii) p-NO2C6H4COCH2CH3. (iii) p-CH3C6H4CHO. (iv) CH3COCH=C(CH3)CH3. (v) CH3COCH2CH(Cl)CH3. (vi) HOOCCH2CH(Br)CH(C6H5)CH3. (vii) p-HOC6H4COC6H4OH-p. (viii) HOOCCH=CHC≡CCH3.
  17. 17. ΔrG° = -45.5 kJ mol^-1; K = 9.7 x 10^7.
  18. 18. (i) Aldol addition followed by reduction. (ii) Aldol condensation with dehydration. (iii) Oxidation of but-2-enal.

📄 Official CBSE Question Papers

Want the real previous-year & sample papers? Download them free from the official board sites:

Practise more — your way

⚙️ Generate unlimited custom papers🎯 Practise MCQs & earn XP

Every paper above is generated from the same 23,000+ verified Brain Grain question bank.