CBSE Class 12 Chemistry 2025 question paper (56/1)

Maximum marks 70 · Time 3 hours · 3 sets

Try each question first, then open its model answer. Where the paper offers a choice, both questions are shown with OR between them.

Section A

1 mark each

Q.11 mark $In case of association, abnormal molar mass of solute will$
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Q.21 mark $\mathrm{Sn^{4+}/Sn^{2+}}$
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Q.31 mark $\mathrm{Cr^{3+}}$
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Q.41 mark $\mathrm{KMnO_4}$
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Q.51 mark $\mathrm{[Pt(NH_3)_2Cl_2]^{2+}}$
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Q.61 mark $\mathrm{(CH_3)_2CH-CH_2Br}$
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Q.71 mark $Alkyl halides undergoing nucleophilic bimolecular substitution reaction involve$
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Q.81 mark $Which is the correct order of acid strength from the following ?$
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Q.91 mark $\mathrm{CO_2}$
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Q.101 mark $The best reagent for converting propanamide into propanamine is ________.$
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Q.111 mark $Which of the following statements is not true about glucose ?$
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Q.121 mark $An unripe mango placed in a concentrated salt solution to prepare pickle, shrivels because ________.$
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For questions number 13 to 16, two statements are given - one labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to these questions from the codes (A), (B), (C) and (D) as given below :
Q.131 mark $\mathrm{[Cr(H_2O)_6]Cl_2}$
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Q.141 mark $Assertion (A) : The boiling points of alkyl halides decrease in the order : RI > RBr > RCl > RF. Reason (R) : The boiling points of alkyl chlorides, bromides and iodides are considerably higher than that of the hydrocarbon of comparable molecular mass.$
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Q.151 mark $Assertion (A) : The boiling point of ethanol is higher than that of methoxymethane. Reason (R) : There is intramolecular hydrogen bonding in ethanol.$
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Q.161 mark $\alpha$
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Section B

2 marks each

Q.17 (A)2 marks $Give reasons : (a) Cooking is faster in pressure cooker than in an open pan. (b) On mixing liquid X and liquid Y, volume of the resulting solution decreases. What type of deviation from Raoult's law is shown by the resulting solution ? What change in temperature would you observe after mixing liquids X and Y ?$
OR
Q.17 (B)2 marks $Define Azeotrope. What type of Azeotrope is formed by negative deviation from Raoult's law ? Give an example.$
Q.182 marks $\mathrm{2MnO_4^{-}(aq) + 10I^{-}(aq) + 16H^{+}(aq)} \longrightarrow$
Q.192 marks $Would you expect benzaldehyde to be more reactive or less reactive in nucleophilic addition reactions than propanal ? Justify your answer.$
Q.202 marks $\mathrm{CH_3CH_2Cl} \xrightarrow{\ \mathrm{NaCN}\ } \mathrm{A} \xrightarrow{\ \mathrm{H_2/Ni}\ } \mathrm{B}$
Q.212 marks $\mathrm{Br_2}$

Section C

3 marks each

Q.223 marks $\mathrm{mol^{-1}}$
Q.233 marks $\mathrm{E^{\circ}_{values}}$
Q.243 marks $\mathrm{K^{-1}\ mol^{-1}}$
Q.253 marks $\mathrm{E^{\circ}_{M^{2+}/M}}$
Q.26 (A)3 marks $\xrightarrow{\ \mathrm{Br_2},\ \text{Heat}\ }$
OR
Q.26 (B)3 marks $How do you convert : (a) Chlorobenzene to biphenyl (b) Propene to 1-Iodopropane (c) 2-bromobutane to but-2-ene.$
Q.273 marks $\mathrm{(CH_3)_2NH}$
Q.283 marks $(a) What is the difference between native protein and denatured protein ? (b) Which one of the following is a disaccharide ? Glucose, Lactose, Amylose, Fructose (c) Which vitamin is responsible for the coagulation of blood ?$

Section D

The rate of a chemical reaction is expressed either in terms of decrease in the concentration of reactants or increase in the concentration of a product per unit time. Rate of the reaction depends upon the nature of reactants, concentration of reactants, temperature, presence of catalyst, surface area of the reactants and presence of light. Rate of reaction is directly related to the concentration of reactant. Rate law states that the rate of reaction depends upon the concentration terms on which the rate of reaction actually depends, as observed experimentally. The sum of powers of the concentration of the reactants in the Rate law expression is called order of reaction while the number of reacting species taking part in an elementary reaction which must collide simultaneously in order to bring about a chemical reaction is called molecularity of the reaction.
Q.29 (a)2 marks $(i) What is a rate determining step ? (ii) Define complex reaction.$
Q.29 (b)1 mark $What is the effect of temperature on the rate constant of a reaction ?$
OR
Q.29 (b) OR1 mark $Why is molecularity applicable only for elementary reactions whereas order is applicable for elementary as well as complex reactions ?$
Q.29 (c)1 mark $The conversion of molecule X to Y follows second order kinetics. If concentration of X is increased 3 times, how will it affect the rate of formation of Y ?$
Phenols undergo electrophilic substitution reactions readily due to the strong activating effect of OH group attached to the benzene ring. Since, the OH group increases the electron density more to o– and p– positions therefore OH group is ortho, para-directing. Reimer-Tiemann reaction is one of the examples of aldehyde group being introduced on the aromatic ring of phenol, ortho to the hydroxyl group. This is a general method used for the ortho-formylation of phenols.
Q.30 (a)2 marks $\mathrm{Br_2/CS_2}$
Q.30 (b)1 mark $Why phenol does not undergo protonation readily ?$
Q.30 (c)1 mark $Which is a stronger acid - phenol or cresol ? Give reason.$
OR
Q.30 (c) OR1 mark $Write the IUPAC name of the product formed in the Reimer-Tiemann reaction.$

Section E

5 marks each

Q.31 (A)5 marks $\mathrm{Sn(s) \mid Sn^{2+}\ (0.004\ M) \parallel H^{+}\ (0.02\ M) \mid H_2(g)\ (1\ Bar) \mid Pt\ (s)}$
OR
Q.31 (B)5 marks $\mathrm{K_2Cr_2O_7(aq)}$
Q.32 (A)5 marks $\mathrm{Co^{2+}}$
OR
Q.32 (B)5 marks $\mathrm{[Fe(CN)_6]^{4-}}$
Q.33 (A)5 marks $\mathrm{C_5H_{10}}$
OR
Q.33 (B)5 marks $\mathrm{C_8H_{16}O_2}$

Section A

1 mark each

For questions number 13 to 16, two statements are given - one labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to these questions from the codes (A), (B), (C) and (D) as given below :
Q.11 mark $\alpha$
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Q.21 mark $Assertion (A) : The boiling point of ethanol is higher than that of methoxymethane. Reason (R) : There is intramolecular hydrogen bonding in ethanol.$
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Q.31 mark $Assertion (A) : The boiling points of alkyl halides decrease in the order : RI > RBr > RCl > RF. Reason (R) : The boiling points of alkyl chlorides, bromides and iodides are considerably higher than that of the hydrocarbon of comparable molecular mass.$
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Q.41 mark $\mathrm{[Cr(H_2O)_6]Cl_2}$
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Q.51 mark $An unripe mango placed in a concentrated salt solution to prepare pickle, shrivels because ________.$
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Q.61 mark $Which of the following statements is not true about glucose ?$
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Q.71 mark $The best reagent for converting propanamide into propanamine is ________.$
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Q.81 mark $\mathrm{CO_2}$
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Q.91 mark $Which is the correct order of acid strength from the following ?$
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Q.101 mark $Alkyl halides undergoing nucleophilic bimolecular substitution reaction involve$
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Q.111 mark $\mathrm{(CH_3)_2CH-CH_2Br}$
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Q.121 mark $\mathrm{[Pt(NH_3)_2Cl_2]^{2+}}$
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Q.131 mark $\mathrm{KMnO_4}$
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Q.141 mark $\mathrm{Cr^{3+}}$
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Q.151 mark $\mathrm{Sn^{4+}/Sn^{2+}}$
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Q.161 mark $In case of association, abnormal molar mass of solute will$
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Section B

2 marks each

Q.172 marks $\mathrm{CH_3CH_2Cl} \xrightarrow{\ \mathrm{NaCN}\ } \mathrm{A} \xrightarrow{\ \mathrm{H_2/Ni}\ } \mathrm{B}$
Q.182 marks $\mathrm{FeCr_2O_4}$
Q.192 marks $Would you expect benzaldehyde to be more reactive or less reactive in nucleophilic addition reactions than propanal ? Justify your answer.$
Q.20 (A)2 marks $Give reasons : (a) Cooking is faster in pressure cooker than in an open pan. (b) On mixing liquid X and liquid Y, volume of the resulting solution decreases. What type of deviation from Raoult's law is shown by the resulting solution ? What change in temperature would you observe after mixing liquids X and Y ?$
OR
Q.20 (B)2 marks $Define Azeotrope. What type of Azeotrope is formed by negative deviation from Raoult's law ? Give an example.$
Q.212 marks $\alpha$

Section C

3 marks each

Q.223 marks $\mathrm{mol^{-1}}$
Q.233 marks $\Delta_r \mathrm{G^{\circ}}$
Q.243 marks $\mathrm{pK_b}$
Q.25 (A)3 marks $\xrightarrow{\ \mathrm{Br_2},\ \text{Heat}\ }$
OR
Q.25 (B)3 marks $How do you convert : (a) Chlorobenzene to biphenyl (b) Propene to 1-Iodopropane (c) 2-bromobutane to but-2-ene.$
Q.263 marks $\mathrm{E^{\circ}_{M^{2+}/M}}$
Q.273 marks $\mathrm{K^{-1}\ mol^{-1}}$
Q.283 marks $\mathrm{NH_2OH}$

Section D

Phenols undergo electrophilic substitution reactions readily due to the strong activating effect of OH group attached to the benzene ring. Since, the OH group increases the electron density more to o– and p– positions therefore OH group is ortho, para-directing. Reimer-Tiemann reaction is one of the examples of aldehyde group being introduced on the aromatic ring of phenol, ortho to the hydroxyl group. This is a general method used for the ortho-formylation of phenols.
Q.29 (a)2 marks $\mathrm{Br_2/CS_2}$
Q.29 (b)1 mark $Why phenol does not undergo protonation readily ?$
Q.29 (c)1 mark $Which is a stronger acid - phenol or cresol ? Give reason.$
OR
Q.29 (c) OR1 mark $Write the IUPAC name of the product formed in the Reimer-Tiemann reaction.$
The rate of a chemical reaction is expressed either in terms of decrease in the concentration of reactants or increase in the concentration of a product per unit time. Rate of the reaction depends upon the nature of reactants, concentration of reactants, temperature, presence of catalyst, surface area of the reactants and presence of light. Rate of reaction is directly related to the concentration of reactant. Rate law states that the rate of reaction depends upon the concentration terms on which the rate of reaction actually depends, as observed experimentally. The sum of powers of the concentration of the reactants in the Rate law expression is called order of reaction while the number of reacting species taking part in an elementary reaction which must collide simultaneously in order to bring about a chemical reaction is called molecularity of the reaction.
Q.30 (a)2 marks $(i) What is a rate determining step ? (ii) Define complex reaction.$
Q.30 (b)1 mark $What is the effect of temperature on the rate constant of a reaction ?$
OR
Q.30 (b) OR1 mark $Why is molecularity applicable only for elementary reactions whereas order is applicable for elementary as well as complex reactions ?$
Q.30 (c)1 mark $The conversion of molecule X to Y follows second order kinetics. If concentration of X is increased 3 times, how will it affect the rate of formation of Y ?$

Section E

5 marks each

Q.31 (A)5 marks $\mathrm{C_5H_{10}}$
OR
Q.31 (B)5 marks $\mathrm{C_8H_{16}O_2}$
Q.32 (A)5 marks $\mathrm{[Fe(en)_2Cl_2]\ Cl}$
OR
Q.32 (B)5 marks $\mathrm{[Co(NH_3)_4\ Cl(NO_2)]Cl}$
Q.33 (A)5 marks $\mathrm{Sn(s) \mid Sn^{2+}\ (0.004\ M) \parallel H^{+}\ (0.02\ M) \mid H_2(g)\ (1\ Bar) \mid Pt\ (s)}$
OR
Q.33 (B)5 marks $\mathrm{K_2Cr_2O_7(aq)}$

Section A

1 mark each

Q.11 mark $\mathrm{Sn^{4+}/Sn^{2+}}$
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Q.21 mark $\mathrm{Cr^{3+}}$
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Q.31 mark $In case of association, abnormal molar mass of solute will$
Tap an option to check your answer.
Q.41 mark $Alkyl halides undergoing nucleophilic bimolecular substitution reaction involve$
Tap an option to check your answer.
Q.51 mark $\mathrm{(CH_3)_2CH-CH_2Br}$
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Q.61 mark $\mathrm{[Pt(NH_3)_2Cl_2]^{2+}}$
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Q.71 mark $\mathrm{CO_2}$
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Q.81 mark $\mathrm{KMnO_4}$
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Q.91 mark $Which is the correct order of acid strength from the following ?$
Tap an option to check your answer.
Q.101 mark $An unripe mango placed in a concentrated salt solution to prepare pickle, shrivels because ________.$
Tap an option to check your answer.
Q.111 mark $The best reagent for converting propanamide into propanamine is ________.$
Tap an option to check your answer.
Q.121 mark $Which of the following statements is not true about glucose ?$
Tap an option to check your answer.
For questions number 13 to 16, two statements are given - one labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to these questions from the codes (A), (B), (C) and (D) as given below :
Q.131 mark $\alpha$
Tap an option to check your answer.
Q.141 mark $Assertion (A) : The boiling point of ethanol is higher than that of methoxymethane. Reason (R) : There is intramolecular hydrogen bonding in ethanol.$
Tap an option to check your answer.
Q.151 mark $Assertion (A) : The boiling points of alkyl halides decrease in the order : RI > RBr > RCl > RF. Reason (R) : The boiling points of alkyl chlorides, bromides and iodides are considerably higher than that of the hydrocarbon of comparable molecular mass.$
Tap an option to check your answer.
Q.161 mark $\mathrm{[Cr(H_2O)_6]Cl_2}$
Tap an option to check your answer.

Section B

2 marks each

Q.172 marks $Would you expect benzaldehyde to be more reactive or less reactive in nucleophilic addition reactions than propanal ? Justify your answer.$
Q.182 marks $\mathrm{8MnO_4^{-} + 3S_2O_3^{2-} + H_2O} \longrightarrow$
Q.19 (A)2 marks $Give reasons : (a) Cooking is faster in pressure cooker than in an open pan. (b) On mixing liquid X and liquid Y, volume of the resulting solution decreases. What type of deviation from Raoult's law is shown by the resulting solution ? What change in temperature would you observe after mixing liquids X and Y ?$
OR
Q.19 (B)2 marks $Define Azeotrope. What type of Azeotrope is formed by negative deviation from Raoult's law ? Give an example.$
Q.202 marks $\mathrm{CH_3CH_2Cl} \xrightarrow{\ \mathrm{NaCN}\ } \mathrm{A} \xrightarrow{\ \mathrm{H_2/Ni}\ } \mathrm{B}$
Q.212 marks $What are the hydrolysis products of : (a) Sucrose (b) Lactose$

Section C

3 marks each

Q.223 marks $\mathrm{CO_2}$
Q.233 marks $\Delta_r G^{\circ}$
Q.243 marks $\mathrm{K^{-1}\ mol^{-1}}$
Q.25 (A)3 marks $\xrightarrow{\ \mathrm{Br_2},\ \text{Heat}\ }$
OR
Q.25 (B)3 marks $How do you convert : (a) Chlorobenzene to biphenyl (b) Propene to 1-Iodopropane (c) 2-bromobutane to but-2-ene.$
Q.263 marks $\mathrm{E^{\circ}_{M^{2+}/M}}$
Q.273 marks $\mathrm{(CH_3)_2NH}$
Q.283 marks $Define the following terms : (a) Native protein (b) Nucleotide (c) Essential amino acid$

Section D

The rate of a chemical reaction is expressed either in terms of decrease in the concentration of reactants or increase in the concentration of a product per unit time. Rate of the reaction depends upon the nature of reactants, concentration of reactants, temperature, presence of catalyst, surface area of the reactants and presence of light. Rate of reaction is directly related to the concentration of reactant. Rate law states that the rate of reaction depends upon the concentration terms on which the rate of reaction actually depends, as observed experimentally. The sum of powers of the concentration of the reactants in the Rate law expression is called order of reaction while the number of reacting species taking part in an elementary reaction which must collide simultaneously in order to bring about a chemical reaction is called molecularity of the reaction.
Q.29 (a)2 marks $(i) What is a rate determining step ? (ii) Define complex reaction.$
Q.29 (b)1 mark $What is the effect of temperature on the rate constant of a reaction ?$
OR
Q.29 (b) OR1 mark $Why is molecularity applicable only for elementary reactions whereas order is applicable for elementary as well as complex reactions ?$
Q.29 (c)1 mark $The conversion of molecule X to Y follows second order kinetics. If concentration of X is increased 3 times, how will it affect the rate of formation of Y ?$
Phenols undergo electrophilic substitution reactions readily due to the strong activating effect of OH group attached to the benzene ring. Since, the OH group increases the electron density more to o– and p– positions therefore OH group is ortho, para-directing. Reimer-Tiemann reaction is one of the examples of aldehyde group being introduced on the aromatic ring of phenol, ortho to the hydroxyl group. This is a general method used for the ortho-formylation of phenols.
Q.30 (a)2 marks $\mathrm{Br_2/CS_2}$
Q.30 (b)1 mark $Why phenol does not undergo protonation readily ?$
Q.30 (c)1 mark $Which is a stronger acid - phenol or cresol ? Give reason.$
OR
Q.30 (c) OR1 mark $Write the IUPAC name of the product formed in the Reimer-Tiemann reaction.$

Section E

5 marks each

Q.31 (A)5 marks $\mathrm{C_5H_{10}}$
OR
Q.31 (B)5 marks $\mathrm{C_8H_{16}O_2}$
Q.32 (A)5 marks $\mathrm{[Fe(H_2O)_6]^{2+}}$
OR
Q.32 (B)5 marks $\mathrm{[Co(H_2O)(CN)(en)_2]^{2+}}$
Q.33 (A)5 marks $\mathrm{Sn(s) \mid Sn^{2+}\ (0.004\ M) \parallel H^{+}\ (0.02\ M) \mid H_2(g)\ (1\ Bar) \mid Pt\ (s)}$
OR
Q.33 (B)5 marks $\mathrm{K_2Cr_2O_7(aq)}$