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Karnataka State Board (PUC) · CLASS 12 SECOND PUC · Chemistry

Karnataka PUC 12th Chemistry Question Paper 2025

75 questions from this CLASS 12 SECOND PUC Chemistry paper. The first 5 questions are solved free; log in as a CLASS 12 SECOND PUC student to view all solutions.

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Home / Previous Year Papers / CLASS 12 SECOND PUC / Chemistry / Karnataka PUC 12th Chemistry Question Paper 2025
Q1 mcq 1 mark
The rate constant of zero order reaction is
  • A. S^{-1}
  • B. mol L^{-1} S
  • C. mol L^{-1} S^{-1}
  • D. mol^{-1} L S^{-1}

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Q2 mcq 1 mark
Which ligand shows linkage isomerism in a coordination complex?
  • A. NO_{2}^{-}
  • B. NH_{3}
  • C. CO
  • D. H_{2}N - CH_{2} - CH_{2} - NH_{2}

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Q2 mcq 1 mark
In a complex, the ligand that shows linkage isomerism is
  • A. $NO_2^-$
  • B. $NH_3$
  • C. CO
  • D. $H_2N - CH_2 - CH_2 - NH_2$

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Q3 mcq 1 mark
The product obtained when $KMnO_{4}$ reacts with $I^{-}$ in weakly basic or neutral medium is
  • A. IO_{3}^{-}
  • B. IMnO_{4}^{+}
  • C. I_{2}
  • D. I_{3}O^{-}

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Q3 mcq 1 mark
The product obtained when $I^-$ reacts with $KMnO_4$ in faintly alkaline or neutral medium is
  • A. $IO_3^-$
  • B. $IMnO_4^+$
  • C. $I_2$
  • D. $I_3O^-$

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Q4 mcq 1 mark
The reagent used in Sandmeyer's reaction is
  • A. Cu_{2}Cl
  • B. Cu and HCl
  • C. Cu_{2}Cl_{2}
  • D. CuCl_{2}

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Q5 mcq 1 mark
10% (w/w) glucose solution in water means
  • A. 10 g of glucose in 100 g of solution
  • B. 10 g of glucose in 10 g of solution
  • C. 10 g of glucose in 90 g of solution
  • D. 10 g of glucose in 90 ml of solution

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Q5 mcq 1 mark
The mass percentage (w/w) of glucose in water is 10% means
  • A. 10g of glucose dissolved in 100g of water.
  • B. 10g of glucose dissolved in 10g of water
  • C. 10g of glucose dissolved in 90g of water
  • D. 10g of glucose dissolved in 90ml of water

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Q6 mcq 1 mark
The bacterial cell wall is made up of ________
  • A. Fructose
  • B. Glycogen
  • C. Starch
  • D. Cellulose

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Q6 mcq 1 mark
Cell wall of bacteria is made of
  • A. Fructose
  • B. Glycogen
  • C. Starch
  • D. Cellulose

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Q7 mcq 1 mark
The most basic amine in aqueous solution is
  • A. Methyl amine
  • B. Dimethyl amine
  • C. Trimethyl amine
  • D. Tetra methyl ammonium ion

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Q8 mcq 1 mark
The method used to separate products obtained when phenol reacts with dil. nitric acid at low temperature
  • A. Simple distillation
  • B. Sublimation
  • C. Crystallization
  • D. Steam distillation

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Q9 mcq 1 mark
In monobromination of phenol, $Br_{2}$ molecule is polarized in
  • A. Presence of strong acid only
  • B. Even in the absence of Lewis acid
  • C. Presence of Lewis acid only
  • D. Presence of strong base only

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Q9 mcq 1 mark
In mono bromination of phenol, the polarisation of Br$_2$ molecule takes place_______
  • A. Only in the presence of strong acid
  • B. Even in the absence of Lewis acid
  • C. Only in the presence of Lewis acid
  • D. Only in the presence of strong base.

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Q10 mcq 1 mark
Which of the following 2M aqueous solution has highest boiling point?
  • A. 2M KCl, (i=2)
  • B. 2M K_{2}SO_{4}, (i=3)
  • C. 2M Al_{2}(SO_{4})_{3}, (i=5)
  • D. 2M K_{3}[Fe(CN)_{6}], (i=4)

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Q10 mcq 1 mark
On assuming complete dissociation, the aqueous solution having highest Freezing point is
  • A. 2M KCl, (i≈2)
  • B. 2M K$_2$SO$_4$, (i≈3)
  • C. 2M Al$_2$(SO$_4$)$_3$, (i≈5)
  • D. 2M K$_3$[Fe(CN)$_6$], (i≈4)

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Q11 mcq 1 mark
The alkyl halide that gives racemic mixture in $S_{N}1$ reaction is
  • A. Tertiary butyl bromide
  • B. 2-chlorobutane
  • C. Isopropyl chloride
  • D. Methyl chloride

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Q12 mcq 1 mark
Statement I: In the graph of $\Lambda_{m}$ vs $c^{1/2}$, the constant 'A' for NaCl and $MgSO_{4}$ is same. Statement II: The value of constant 'A' is same for all electrolytes of a particular type.
  • A. Statement I and Statement II are true
  • B. Statement I and Statement II are false
  • C. Statement I is true and Statement II is false
  • D. Statement I is false and Statement II is true

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Q12 mcq 1 mark
Statement I: NaCl and MgSO$_4$ has same value of constant 'A' in plot of $\lambda_m$ against c$^{1/2}$. Statement II: All electrolytes of a particular type have the same value of 'A'
  • A. Both statement I and II are correct
  • B. Both statement I and II are incorrect
  • C. Statement I is correct but statement II is incorrect
  • D. Statement I is incorrect but statement II is correct.

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Q13 mcq 1 mark
For the coordination compound $PtBr_{2} \cdot 4NH_{3}$, the reaction with excess $AgNO_{3}$ gives two moles of AgBr precipitate. The secondary and primary valencies of the metal ion in this complex are
  • A. 4 and 4
  • B. 6 and 2
  • C. 6 and 4
  • D. 4 and 2

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Q13 mcq 1 mark
Co-ordination complex with composition PtBr$_2$·4NH$_3$ on reacting with excess of AgNO$_3$ produces two moles of AgBr precipitate. The secondary and primary valence of the metal ion in this complex is
  • A. 4 and 4
  • B. 6 and 2
  • C. 6 and 4
  • D. 4 and 2

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Q14 mcq 1 mark
Benzaldehyde undergoes reduction in Cannizzaro reaction to give _________
  • A. Sodium benzoate and benzyl alcohol
  • B. Benzoic acid and benzyl alcohol
  • C. Sodium benzoate only
  • D. Benzyl alcohol only

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Q14 mcq 1 mark
In cannizzaro reaction, benzaldehyde is reduced to produce _________
  • A. Sodium benzoate and Benzyl alcohol
  • B. Benzoic acid and Benzyl alcohol
  • C. Sodium benzoate only
  • D. Benzyl alcohol only.

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Q15 mcq 1 mark
Tripeptide _________.
  • A. Contains 3 amino acids and 2 peptide linkages
  • B. Contains 3 amino acids and 3 peptide linkages
  • C. Contains 2 amino acids and 3 peptide linkages
  • D. Contains 3 amino acids and 4 peptide linkages

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Q15 mcq 1 mark
A tripeptide contains _______
  • A. Three amino acids and two peptide linkages
  • B. Three amino acids and three peptide linkages
  • C. Two amino acids and three peptide linkages
  • D. Three amino acids and four peptide linkages

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Q16 short answer 1 mark
The solubility of gases in liquid increases with increase in _________.

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Q16 short answer 1 mark
As temperature increases solubility of gases in liquid _______.

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Q17 short answer 1 mark
The number of hydroxyl groups present in ethylene glycol is _________.

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Q18 short answer 1 mark
The number of non-bonding electron pairs on nitrogen atom in dimethyl amine is _________.

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Q18 short answer 1 mark
The number of lone pair of electron present on nitrogen atom in dimethylamine is ______.

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Q19 short answer 1 mark
The 3d series metal with positive electrode potential is _________.

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Q19 short answer 1 mark
The element of 3d series to have positive standard electrode potential is ______.

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Q20 short answer 1 mark
Oxidation of secondary alcohol produces _________.

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Q20 short answer 1 mark
Secondary alcohol on oxidation produces _______.

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Q21 short answer 2 marks
Define coordination number. Write the coordination number of the central metal ion in the complex $[Ni(NH_{3})_{6}]^{2+}$.

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Q21 short answer 2 marks
Define collision frequency. Mention any one factor that affects effective collisions.

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Q22 short answer 2 marks
Name any two transition metals found in U.K. coinage.

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Q22 short answer 2 marks
Name the two main transition metals found in 'UK silver' coins.

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Q23 short answer 2 marks
Name the two fat-soluble vitamins stored in the human body.

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Q23 short answer 2 marks
Name two fat storing tissues found in human body that stores fat soluble vitamins.

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Q24 short answer 2 marks
Explain Fittig reaction with a suitable chemical equation.

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Q25 short answer 2 marks
Classify anisole and diethyl ether as simple and mixed ethers.

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Q25 short answer 2 marks
Classify Anisole and methoxymethane into simple ether and mixed ether.

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Q26 long answer 3 marks
Explain the hybridization, magnetic property and geometry of $[Ni(CN)_{4}]^{2-}$ based on Valence Bond Theory [VBT]. (Atomic number of Ni = 28)

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Q26 long answer 3 marks
Using Valence Bond Theory [VBT], explain hybridisation, magnetic property and geometry of [Ni(CN)$_4$]$^{2-}$ (Atomic no. of Ni is 28)

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Q27 long answer 3 marks
Write the balanced chemical equations involved in the production of potassium dichromate from chromite ore.

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Q28 long answer 3 marks
Mention any three postulates of Werner's theory of coordination compounds.

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Q28 long answer 3 marks
Write any three postulates of Werner's theory.

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Q29 long answer 3 marks
(a) Name two colorless trivalent lanthanoid ions. (b) What type of lanthanoid compounds are used as catalysts in petroleum cracking?

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Q30 long answer 3 marks
How many square pyramidal units are there in Decacarbonyl dimanganese(0)? Write its chemical formula and structure.

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Q31 long answer 3 marks
What are colligative properties? Name the colligative property expressed in terms of mole fraction. Write the mathematical equation of that colligative property.

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Q32 long answer 3 marks
Name the fuel cell used in Apollo space programme. Write its anodic and cathodic reactions.

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Q33 long answer 3 marks
Derive an integrated rate equation for rate constant of First order reaction.

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Q41 long answer 3 marks
400 $cm^3$ of an aqueous solution of a protein contains 2.52g of the protein. The osmotic pressure of such a solution at 300k is found to be 2.57 × $10^{–3}$ bar. Calculate the molar mass of the protein [R = 0.083L bar $mol^{–1}$ $K^{–1}$].

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Q42 long answer 3 marks
The following reaction takes place in the cell. $Mg_{(s)} + 2Ag^+_{(0.0001M)} \rightarrow Mg^{2+}_{(0.2m)} + 2Ag_{(s)}$. If $E^o_{cell} = 3.17V$, calculate the $E_{cell}$ at 298k.

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Q43 long answer 3 marks
The initial concentration of $N_2O_5$ in the following first order reaction $N_2O_{5(g)} \rightarrow 2NO_{2(g)} + \frac{1}{2}O_{2(g)}$ was 1.24 × $10^{–2}$ mol $L^{–1}$ at 318k. The concentration of $N_2O_5$ after 60 minutes was 0.20 × $10^{–2}$ mol $L^{–1}$. Calculate the rate constant of the reaction at 318K.

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Q44 long answer 3 marks
The vapour pressure of pure liquids A and B are 450 and 700 mm Hg respectively at 350K. Find out the vapour pressure of solution 'A' if the total vapour pressure of solution is 600 mm Hg.

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Q45 long answer 3 marks
If a current of 0.5 ampere flows through a metallic wire for 2 hours, then how many electrons would flow through the wire?

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Q46 long answer 3 marks
The activation energy for reaction, $2HI_{(g)} \rightarrow H_{2(g)} + I_{2(g)}$ is 209.5 KJ$mol^{–1}$ at 581K. Calculate the fraction of molecules of reactants having energy equal to or greater than activation energy.

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Q51 short answer 2 marks
Name two trivalent lanthanoid ions that are colourless.

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Q52 short answer 1 mark
What type of lanthanoid compounds are employed as catalyst in petroleum cracking?

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Q56 short answer 1 mark
State Faraday's 1st Law of electrolysis

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Q57 short answer 2 marks
Mention any two factors that determines the product of electrolysis.

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Q58 long answer 3 marks
Write the mechanism of $S_N1$ reaction involved in the hydrolysis of tertiary butyl bromide. Mention the reactant on which rate of reaction depends in above reaction.

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Q59 long answer 2 marks
Explain Zaytsev (saytzeff) rule with suitable chemical equation.

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Q60 long answer 2 marks
Write the Haworth structure of Maltose.

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Q61 long answer 2 marks
What are globular proteins? Give one example for it.

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Q62 long answer 1 mark
Name the nitrogen base present in RNA and absent in DNA.

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Q63 long answer 3 marks
Among acetaldehyde and benzaldehyde which one undergoes aldol condensation reaction? Explain its aldol condensation with equation.

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Q64 long answer 3 marks
Write the steps in mechanism of acid catalysed hydrolysis of ethene to ethanol.

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Q65 long answer 2 marks
Between p-nitrophenol and p-cresol which has highest pKa and least pKa values?

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Q66 long answer 3 marks
Write the chemical equations involved in Gabriel pthalimide synthesis for the preparation of methylamine.

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Q67 long answer 2 marks
Name the reducing agent most preferred to reduce nitrobenzene to Aniline. Justify your answer.

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Q68 long answer 3 marks
Compound 'A' with formula $C_7H_8$ on heating with alkaline $KMnO_4$ and on further acidification produces compound B. Compound B on heating with ammonia at high temperature gives Compound 'C' with formula $C_7H_7NO$. Write the structure of compounds A, B and C.

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Q69 long answer 2 marks
Whether Aromatic Carboxylic acid undergoes Friedel-Crafts reaction? Give correct reason for it.

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