CBSE Class 12 Chemistry 2025 question paper (56/2)

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 $\mathrm{MnO_4^{-}}$
Tap an option to check your answer.
Q.21 mark $Which among the following is a false statement ?$
Tap an option to check your answer.
Q.31 mark $The number of molecules that react with each other in an elementary reaction is a measure of the :$
Tap an option to check your answer.
Q.41 mark $\mathrm{[Ar]3d^{10}4s^{1}}$
Tap an option to check your answer.
Q.51 mark $\mathrm{[Co(NH_3)_5(NO_2)]^{2+}}$
Tap an option to check your answer.
Q.61 mark $The diamagnetic species is : [At. No. Co = 27, Fe = 26, Ni = 28]$
Tap an option to check your answer.
Q.71 mark $Which is the correct IUPAC name for$
Tap an option to check your answer.
Q.81 mark $\mathrm{(CrO_3)}$
Tap an option to check your answer.
Q.91 mark $The conversion of phenol to salicylic acid can be accomplished by$
Tap an option to check your answer.
Q.101 mark $Which of the following is/are examples of denaturation of protein ?$
Tap an option to check your answer.
Q.111 mark $Nucleotides are joined together by$
Tap an option to check your answer.
Q.121 mark $Scurvy is caused due to deficiency of$
Tap an option to check your answer.
For question 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 $Assertion (A) : In a first order reaction, if the concentration of the reactant is doubled, its half-life is also doubled. Reason (R) : The half-life of a reaction does not depend upon the initial concentration of the reactant in a first order reaction.$
Tap an option to check your answer.
Q.141 mark $\mathrm{H_2}$
Tap an option to check your answer.
Q.151 mark $Assertion (A) : Aromatic primary amines cannot be prepared by Gabriel Phthalimide synthesis. Reason (R) : Aryl halides do not undergo nucleophilic substitution reaction with the anion formed by phthalimide.$
Tap an option to check your answer.
Q.161 mark $Assertion (A) : Vitamin D cannot be stored in our body. Reason (R) : Vitamin D is fat soluble vitamin and is not excreted from the body in urine.$
Tap an option to check your answer.

Section B

2 marks each

Q.17 (A)2 marks $\mathrm{A} \rightarrow \mathrm{P}$
OR
Q.17 (B)2 marks $\mathrm{NH_3}$
Q.182 marks $\mathrm{(t_{1/2})}$
Q.192 marks $Examine the following observations : (a) Transition elements generally form coloured compounds. (b) Zinc is not regarded as a transition element.$
Q.202 marks $\mathrm{[Co(NH_3)_4(H_2O)Cl]Cl_2}$
Q.212 marks $\mathrm{S_N1}$

Section C

3 marks each

Q.223 marks $\mathrm{mol^{-1}}$
Q.233 marks $\mathrm{cm^2}$
Q.243 marks $\mathrm{MnO_4^{-}} + \mathrm{C_2O_4^{2-}} + \mathrm{H^{+}} \longrightarrow$
Q.253 marks $\mathrm{[Co(NH_3)_6]^{3+}}$
Q.263 marks $(a) Define the following : (i) Enantiomers (ii) Racemic mixture (b) Why is chlorobenzene resistant to nucleophilic substitution reaction ?$
Q.27 (A)3 marks $Explain the following reactions and write chemical equation involved : (a) Wolff-Kishner reduction (b) Etard reaction (c) Cannizzaro reaction$
OR
Q.27 (B)3 marks $\mathrm{CH_3COOH} \xrightarrow{\mathrm{SOCl_2}} \mathrm{A} \xrightarrow{\mathrm{H_2},\ \text{Pd-BaSO}_4} \mathrm{B} \xrightarrow{\mathrm{H_2N-NH_2}} \mathrm{C}$
Q.283 marks $Define the following terms : (a) Glycosidic linkage (b) Invert sugar (c) Oligosaccharides$

Section D

The spontaneous flow of the solvent through a semipermeable membrane from a pure solvent to a solution or from a dilute solution to a concentrated solution is called osmosis. The phenomenon of osmosis can be demonstrated by taking two eggs of the same size. In an egg, the membrane below the shell and around the egg material is semipermeable. The outer hard shell can be removed by putting the egg in dilute hydrochloric acid. After removing the hard shell, one egg is placed in distilled water and the other in a saturated salt solution. After some time, the egg placed in distilled water swells-up while the egg placed in salt solution shrinks. The external pressure applied to stop the osmosis is termed as osmotic pressure (a colligative property). Reverse osmosis takes place when the applied external pressure becomes larger than the osmotic pressure.
Q.29 (a)2 marks $Define reverse osmosis. Name one SPM which can be used in the process of reverse osmosis.$
Q.29 (b) (i)1 mark $\mathrm{NaCl}$
OR
Q.29 (b) (ii)1 mark $\mathrm{KCl}$
Q.29 (c)1 mark $Why osmotic pressure is a colligative property ?$
Amines have a lone pair of electrons on nitrogen atom due to which they behave as Lewis base. Greater the value of $\mathrm{K_b}$ or smaller the value of $\mathrm{pK_b}$ , stronger is the base. Amines are more basic than alcohols, ethers, esters, etc. The basic character of aliphatic amines should increase with the increase of alkyl substitution. But it does not occur in a regular manner as a secondary aliphatic amine is unexpectedly more basic than a tertiary amine in aqueous solutions. Aromatic amines are weaker bases than ammonia and aliphatic amines. Electron releasing groups such as $\mathrm{-CH_3}$ , $\mathrm{-OCH_3}$ , $\mathrm{-NH_2}$ , etc., increase the basicity while electron-withdrawing substituents such as $\mathrm{-NO_2}$ , $\mathrm{-CN}$ , halogens etc., decrease the basicity of amines. The effect of these substitute is more at $\mathrm{p}^{-}$ than at $\mathrm{m}^{-}$ position.
Q.30 (a)2 marks $Arrange the following in the increasing order of their basic character. Give reason :$
Q.30 (b)1 mark $\mathrm{pK_b}$
Q.30 (c) (i)1 mark $\mathrm{(CH_3)_3N},\ \mathrm{(CH_3)_2NH},\ \mathrm{NH_3},\ \mathrm{CH_3NH_2}$
OR
Q.30 (c) (ii)1 mark $Why ammonolysis of alkyl halides is not a good method to prepare pure amines ?$

Section E

5 marks each

Q.31 (A)5 marks $\mathrm{CH_3-CH=CH-CHO}$
OR
Q.31 (B)5 marks $Complete each synthesis by giving missing starting material, reagent or products :$
Q.32 (A)5 marks $(\Delta_\mathrm{r}\mathrm{G}^{\circ})$
OR
Q.32 (B)5 marks $\mathrm{Zn(s)} \mid \mathrm{Zn^{2+}_{(0.1M)}} \parallel \mathrm{Cd^{2+}_{(0.01M)}} \mid \mathrm{Cd(s)}$
Q.33 (A)5 marks $\mathrm{C_2H_6O}$
OR
Q.33 (B)5 marks $\mathrm{HNO_3}$

Section A

1 mark each

For question 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 $Assertion (A) : Vitamin D cannot be stored in our body. Reason (R) : Vitamin D is fat soluble vitamin and is not excreted from the body in urine.$
Tap an option to check your answer.
Q.21 mark $Assertion (A) : Aromatic primary amines cannot be prepared by Gabriel Phthalimide synthesis. Reason (R) : Aryl halides do not undergo nucleophilic substitution reaction with the anion formed by phthalimide.$
Tap an option to check your answer.
Q.31 mark $\mathrm{H_2}$
Tap an option to check your answer.
Q.41 mark $Assertion (A) : In a first order reaction, if the concentration of the reactant is doubled, its half-life is also doubled. Reason (R) : The half-life of a reaction does not depend upon the initial concentration of the reactant in a first order reaction.$
Tap an option to check your answer.
Q.51 mark $Scurvy is caused due to deficiency of$
Tap an option to check your answer.
Q.61 mark $Nucleotides are joined together by$
Tap an option to check your answer.
Q.71 mark $Which of the following is/are examples of denaturation of protein ?$
Tap an option to check your answer.
Q.81 mark $The conversion of phenol to salicylic acid can be accomplished by$
Tap an option to check your answer.
Q.91 mark $\mathrm{(CrO_3)}$
Tap an option to check your answer.
Q.101 mark $Which is the correct IUPAC name for$
Tap an option to check your answer.
Q.111 mark $The diamagnetic species is : [At. No. Co = 27, Fe = 26, Ni = 28]$
Tap an option to check your answer.
Q.121 mark $\mathrm{[Co(NH_3)_5(NO_2)]^{2+}}$
Tap an option to check your answer.
Q.131 mark $\mathrm{[Ar]3d^{10}4s^{1}}$
Tap an option to check your answer.
Q.141 mark $The number of molecules that react with each other in an elementary reaction is a measure of the :$
Tap an option to check your answer.
Q.151 mark $Which among the following is a false statement ?$
Tap an option to check your answer.
Q.161 mark $\mathrm{MnO_4^{-}}$
Tap an option to check your answer.

Section B

2 marks each

Q.172 marks $\mathrm{S_N1}$
Q.182 marks $A reaction is of second order with respect to a reactant. How is the rate of reaction affected if the concentration of the reactant is (i) doubled (ii) reduced to half ?$
Q.192 marks $\mathrm{FeCr_2O_4}$
Q.202 marks $\mathrm{[Co(NH_3)_6]^{3+}}$
Q.21 (A)2 marks $\mathrm{A} \rightarrow \mathrm{P}$
OR
Q.21 (B)2 marks $\mathrm{NH_3}$

Section C

3 marks each

Q.223 marks $\mathrm{mol^{-1}}$
Q.233 marks $\Lambda^{\circ}\mathrm{m}$
Q.243 marks $\mathrm{d^4}$
Q.253 marks $\mathrm{[Fe(en)_2Cl_2]^{+}}$
Q.26 (A)3 marks $Explain the following reactions and write chemical equation involved : (a) Wolff-Kishner reduction (b) Etard reaction (c) Cannizzaro reaction$
OR
Q.26 (B)3 marks $\mathrm{CH_3COOH} \xrightarrow{\mathrm{SOCl_2}} \mathrm{A} \xrightarrow{\mathrm{H_2},\ \text{Pd-BaSO}_4} \mathrm{B} \xrightarrow{\mathrm{H_2N-NH_2}} \mathrm{C}$
Q.273 marks $(a) Define the following : (i) Enantiomers (ii) Racemic mixture (b) Why is chlorobenzene resistant to nucleophilic substitution reaction ?$
Q.283 marks $\mathrm{H_2N-OH}$

Section D

Amines have a lone pair of electrons on nitrogen atom due to which they behave as Lewis base. Greater the value of $\mathrm{K_b}$ or smaller the value of $\mathrm{pK_b}$ , stronger is the base. Amines are more basic than alcohols, ethers, esters, etc. The basic character of aliphatic amines should increase with the increase of alkyl substitution. But it does not occur in a regular manner as a secondary aliphatic amine is unexpectedly more basic than a tertiary amine in aqueous solutions. Aromatic amines are weaker bases than ammonia and aliphatic amines. Electron releasing groups such as $\mathrm{-CH_3}$ , $\mathrm{-OCH_3}$ , $\mathrm{-NH_2}$ , etc., increase the basicity while electron-withdrawing substituents such as $\mathrm{-NO_2}$ , $\mathrm{-CN}$ , halogens etc., decrease the basicity of amines. The effect of these substitute is more at $\mathrm{p}^{-}$ than at $\mathrm{m}^{-}$ position.
Q.29 (a)2 marks $Arrange the following in the increasing order of their basic character. Give reason :$
Q.29 (b)1 mark $\mathrm{pK_b}$
Q.29 (c) (i)1 mark $\mathrm{(CH_3)_3N},\ \mathrm{(CH_3)_2NH},\ \mathrm{NH_3},\ \mathrm{CH_3NH_2}$
OR
Q.29 (c) (ii)1 mark $Why ammonolysis of alkyl halides is not a good method to prepare pure amines ?$
The spontaneous flow of the solvent through a semipermeable membrane from a pure solvent to a solution or from a dilute solution to a concentrated solution is called osmosis. The phenomenon of osmosis can be demonstrated by taking two eggs of the same size. In an egg, the membrane below the shell and around the egg material is semipermeable. The outer hard shell can be removed by putting the egg in dilute hydrochloric acid. After removing the hard shell, one egg is placed in distilled water and the other in a saturated salt solution. After some time, the egg placed in distilled water swells-up while the egg placed in salt solution shrinks. The external pressure applied to stop the osmosis is termed as osmotic pressure (a colligative property). Reverse osmosis takes place when the applied external pressure becomes larger than the osmotic pressure.
Q.30 (a)2 marks $Define reverse osmosis. Name one SPM which can be used in the process of reverse osmosis.$
Q.30 (b) (i)1 mark $\mathrm{NaCl}$
OR
Q.30 (b) (ii)1 mark $\mathrm{KCl}$
Q.30 (c)1 mark $Why osmotic pressure is a colligative property ?$

Section E

5 marks each

Q.31 (A)5 marks $\mathrm{C_2H_6O}$
OR
Q.31 (B)5 marks $\mathrm{HNO_3}$
Q.32 (A)5 marks $\mathrm{CH_3-CH=CH-CHO}$
OR
Q.32 (B)5 marks $Complete each synthesis by giving missing starting material, reagent or products :$
Q.33 (A)5 marks $(\Delta_\mathrm{r}\mathrm{G}^{\circ})$
OR
Q.33 (B)5 marks $\mathrm{Zn(s)} \mid \mathrm{Zn^{2+}_{(0.1M)}} \parallel \mathrm{Cd^{2+}_{(0.01M)}} \mid \mathrm{Cd(s)}$

Section A

1 mark each

Q.11 mark $Which among the following is a false statement ?$
Tap an option to check your answer.
Q.21 mark $\mathrm{MnO_4^{-}}$
Tap an option to check your answer.
Q.31 mark $\mathrm{[Ar]3d^{10}4s^{1}}$
Tap an option to check your answer.
Q.41 mark $The number of molecules that react with each other in an elementary reaction is a measure of the :$
Tap an option to check your answer.
Q.51 mark $The diamagnetic species is : [At. No. Co = 27, Fe = 26, Ni = 28]$
Tap an option to check your answer.
Q.61 mark $\mathrm{[Co(NH_3)_5(NO_2)]^{2+}}$
Tap an option to check your answer.
Q.71 mark $\mathrm{(CrO_3)}$
Tap an option to check your answer.
Q.81 mark $Which is the correct IUPAC name for$
Tap an option to check your answer.
Q.91 mark $Which of the following is/are examples of denaturation of protein ?$
Tap an option to check your answer.
Q.101 mark $The conversion of phenol to salicylic acid can be accomplished by$
Tap an option to check your answer.
Q.111 mark $Scurvy is caused due to deficiency of$
Tap an option to check your answer.
Q.121 mark $Nucleotides are joined together by$
Tap an option to check your answer.
For question 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 $\mathrm{H_2}$
Tap an option to check your answer.
Q.141 mark $Assertion (A) : In a first order reaction, if the concentration of the reactant is doubled, its half-life is also doubled. Reason (R) : The half-life of a reaction does not depend upon the initial concentration of the reactant in a first order reaction.$
Tap an option to check your answer.
Q.151 mark $Assertion (A) : Vitamin D cannot be stored in our body. Reason (R) : Vitamin D is fat soluble vitamin and is not excreted from the body in urine.$
Tap an option to check your answer.
Q.161 mark $Assertion (A) : Aromatic primary amines cannot be prepared by Gabriel Phthalimide synthesis. Reason (R) : Aryl halides do not undergo nucleophilic substitution reaction with the anion formed by phthalimide.$
Tap an option to check your answer.

Section B

2 marks each

Q.172 marks $\mathrm{[Co(NH_3)_4(H_2O)Cl]Cl_2}$
Q.182 marks $\mathrm{s^{-1}}$
Q.192 marks $\mathrm{8MnO_4^{-}} + \mathrm{3S_2O_3^{2-}} + \mathrm{H_2O} \longrightarrow$
Q.20 (A)2 marks $\mathrm{A} \rightarrow \mathrm{P}$
OR
Q.20 (B)2 marks $\mathrm{NH_3}$
Q.212 marks $Give reasons for the following observations : (a) p-Chloronitrobenzene reacts with (aq)NaOH at 443 K to give p-nitrophenol whereas chlorobenzene reacts with the same reagent at 623 K and 300 atm. (b) Main product obtained when chloroethane reacts with KCN is propane nitrile while with Ag CN it is ethyl isocyanide.$

Section C

3 marks each

Q.223 marks $\mathrm{CO_2}$
Q.233 marks $Give reasons : (a) Fuel cells are preferred for production of electrical energy than thermal plants. (b) Iron does not rust even if zinc coating is broken in a galvanized pipe. (c) In the experimental determination of electrolytic conductance, Direct Current (DC) is not used.$
Q.243 marks $\mathrm{E}^{\circ}_{(\mathrm{Mn^{2+}/Mn})}$
Q.253 marks $\mathrm{[Co(NH_3)_6]Cl_3}$
Q.263 marks $(a) Define the following : (i) Enantiomers (ii) Racemic mixture (b) Why is chlorobenzene resistant to nucleophilic substitution reaction ?$
Q.27 (A)3 marks $Explain the following reactions and write chemical equation involved : (a) Wolff-Kishner reduction (b) Etard reaction (c) Cannizzaro reaction$
OR
Q.27 (B)3 marks $\mathrm{CH_3COOH} \xrightarrow{\mathrm{SOCl_2}} \mathrm{A} \xrightarrow{\mathrm{H_2},\ \text{Pd-BaSO}_4} \mathrm{B} \xrightarrow{\mathrm{H_2N-NH_2}} \mathrm{C}$
Q.283 marks $Define the following terms : (a) Native protein (b) Nucleotide (c) Essential amino acid$

Section D

The spontaneous flow of the solvent through a semipermeable membrane from a pure solvent to a solution or from a dilute solution to a concentrated solution is called osmosis. The phenomenon of osmosis can be demonstrated by taking two eggs of the same size. In an egg, the membrane below the shell and around the egg material is semipermeable. The outer hard shell can be removed by putting the egg in dilute hydrochloric acid. After removing the hard shell, one egg is placed in distilled water and the other in a saturated salt solution. After some time, the egg placed in distilled water swells-up while the egg placed in salt solution shrinks. The external pressure applied to stop the osmosis is termed as osmotic pressure (a colligative property). Reverse osmosis takes place when the applied external pressure becomes larger than the osmotic pressure.
Q.29 (a)2 marks $Define reverse osmosis. Name one SPM which can be used in the process of reverse osmosis.$
Q.29 (b) (i)1 mark $\mathrm{NaCl}$
OR
Q.29 (b) (ii)1 mark $\mathrm{KCl}$
Q.29 (c)1 mark $Why osmotic pressure is a colligative property ?$
Amines have a lone pair of electrons on nitrogen atom due to which they behave as Lewis base. Greater the value of $\mathrm{K_b}$ or smaller the value of $\mathrm{pK_b}$ , stronger is the base. Amines are more basic than alcohols, ethers, esters, etc. The basic character of aliphatic amines should increase with the increase of alkyl substitution. But it does not occur in a regular manner as a secondary aliphatic amine is unexpectedly more basic than a tertiary amine in aqueous solutions. Aromatic amines are weaker bases than ammonia and aliphatic amines. Electron releasing groups such as $\mathrm{-CH_3}$ , $\mathrm{-OCH_3}$ , $\mathrm{-NH_2}$ , etc., increase the basicity while electron-withdrawing substituents such as $\mathrm{-NO_2}$ , $\mathrm{-CN}$ , halogens etc., decrease the basicity of amines. The effect of these substitute is more at $\mathrm{p}^{-}$ than at $\mathrm{m}^{-}$ position.
Q.30 (a)2 marks $Arrange the following in the increasing order of their basic character. Give reason :$
Q.30 (b)1 mark $\mathrm{pK_b}$
Q.30 (c) (i)1 mark $\mathrm{(CH_3)_3N},\ \mathrm{(CH_3)_2NH},\ \mathrm{NH_3},\ \mathrm{CH_3NH_2}$
OR
Q.30 (c) (ii)1 mark $Why ammonolysis of alkyl halides is not a good method to prepare pure amines ?$

Section E

5 marks each

Q.31 (A)5 marks $(\Delta_\mathrm{r}\mathrm{G}^{\circ})$
OR
Q.31 (B)5 marks $\mathrm{Zn(s)} \mid \mathrm{Zn^{2+}_{(0.1M)}} \parallel \mathrm{Cd^{2+}_{(0.01M)}} \mid \mathrm{Cd(s)}$
Q.32 (A)5 marks $\mathrm{C_2H_6O}$
OR
Q.32 (B)5 marks $\mathrm{HNO_3}$
Q.33 (A)5 marks $\mathrm{CH_3-CH=CH-CHO}$
OR
Q.33 (B)5 marks $Complete each synthesis by giving missing starting material, reagent or products :$