CBSE Class 12 Chemistry 2025 question paper (56/6)

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 $Williamson synthesis of preparing unsymmetrical ether is :$
Tap an option to check your answer.
Q.21 mark $Which of the following compounds would be hydrolysed by aqueous KOH most easily ?$
Tap an option to check your answer.
Q.31 mark $According to Werner’s theory of coordination compounds :$
Tap an option to check your answer.
Q.41 mark $Which of the following complex ion is not optically active ?$
Tap an option to check your answer.
Q.51 mark $Which of the following is the softest metal ?$
Tap an option to check your answer.
Q.61 mark $In the Hinsberg’s method for separation of primary, secondary and tertiary amines, the reagent used is :$
Tap an option to check your answer.
Q.71 mark $\mathrm{HNO_2}$
Tap an option to check your answer.
Q.81 mark $\mathrm{K_f}$
Tap an option to check your answer.
Q.91 mark $A solution of acetone in ethanol :$
Tap an option to check your answer.
Q.101 mark $Which of the following cell converts the energy of combustion of fuel into electrical energy ?$
Tap an option to check your answer.
Q.111 mark $The unit of rate and rate constant are same for a :$
Tap an option to check your answer.
Q.121 mark $Pyranose ring of glucose is formed due to the reaction between :$
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 $Assertion (A) : Actinoids show wide range of oxidation states. Reason (R) : Actinoids are radioactive in nature.$
Tap an option to check your answer.
Q.141 mark $Assertion (A) : Hydrolysis of an ester follows first order kinetics. Reason (R) : The concentration of water does not get altered much during the reaction.$
Tap an option to check your answer.
Q.151 mark $\mathrm{(CH_3)_3N}$
Tap an option to check your answer.
Q.161 mark $Assertion (A) : Phenol is strongly acidic as compared to ethanol. Reason (R) : Phenoxide ion is more stable than ethoxide ion.$
Tap an option to check your answer.

Section B

2 marks each

Q.172 marks $State Henry’s law. Why are aquatic species more comfortable in cold water as compared to warm water ?$
Q.182 marks $Observe the graph in the given figure and answer the following questions : (a) Predict the order of reaction. (b) What is the slope of the curve ?$
Q.19 (a)2 marks $\mathrm{[CoCl_2(en)_2]SO_4}$
OR
Q.19 (b)2 marks $Differentiate between : (i) Double salt and Complex compound (ii) Didentate ligand and Ambidentate ligand$
Q.202 marks $\longrightarrow$
Q.212 marks $How do you explain the following ? (a) Presence of an aldehydic group in glucose. (b) Presence of five - OH groups in glucose.$

Section C

3 marks each

Q.223 marks $24{\cdot}8$

Q.233 marks

\longrightarrow

Q.243 marks $Give reasons for the following : (a) The pH of aqueous NaCl increases when it is electrolysed. (b) Unlike dry cell, mercury cell has a constant cell potential through its lifetime. (c) Conductivity of solution decreases with dilution.$
Q.25 (a)3 marks $\mathrm{[FeF_6]^{3-}}$
OR
Q.25 (b)3 marks $\mathrm{[Ti(H_2O)_6]^{3+}}$
Q.263 marks $\mathrm{S_N}1$
Q.273 marks $\mathrm{C_4H_5N}$
Q.283 marks $How will you obtain the following from aniline ? Give chemical equations only. (a) Sulphanilic acid (b) Phenylisocyanide (c) Acetanilide$

Experiment	[A] / mol $\mathrm{L^{-1}}$	[B] / mol $\mathrm{L^{-1}}$	Initial Rate/mol $\mathrm{L^{-1}\,min^{-1}}$
1	$0{\cdot}01$	$0{\cdot}01$	$5 \times 10^{-3}$
2	$0{\cdot}02$	$0{\cdot}01$	$1 \times 10^{-2}$
3	$0{\cdot}01$	$0{\cdot}02$	$5 \times 10^{-3}$

Section D

Alcohols undergo a number of reactions involving the cleavage of C – OH bond. However, phenols do not undergo reactions involving the cleavage of C – OH bond. Alcohols are weaker acids than water. Alcohols react with halogen acids to form the corresponding haloalkanes. Phenols are stronger acids than alcohols. A characteristic feature of phenols is that they undergo electrophilic substitution reactions such as halogenation, nitration, etc. Since – OH group is a strong activating group, phenol gives trisubstituted products during halogenation, nitration, etc.
Q.29 (a)2 marks $\mathrm{Br_2}$
Q.29 (b) (i)1 mark $\mathrm{CH_3^{\oplus}}$
OR
Q.29 (b) (ii)1 mark $Why do phenols not undergo reactions involving cleavage of C - OH bond ?$
Q.29 (c)1 mark $\mathrm{ZnCl_2}$
The $\alpha$ -amino acids are the building blocks of proteins. All $\alpha$ -amino acids exist as zwitter ion due to which they show amphoteric behaviour. All amino acids are joined through peptide bond. Proteins are broadly classified as globular proteins and fibrous proteins. Globular proteins are water soluble, whereas fibrous proteins are not. The complete structure of protein is discussed at four different levels i.e. primary, secondary, tertiary and quaternary structures. Protein loses its biological activity in denatured form.
Q.30 (a)2 marks $Define the following : (i) Peptide linkage (ii) Denatured protein$
Q.30 (b)1 mark $Why do amino acids show amphoteric behaviour ?$
Q.30 (c) (i)1 mark $How can you differentiate between Fibrous protein and Globular protein ?$
OR
Q.30 (c) (ii)1 mark $Write the names of two different secondary structures of proteins.$

Section E

5 marks each

Q.31 (a)5 marks $\mathrm{E_{cell}}$
OR
Q.31 (b)5 marks $0{\cdot}001$
Q.32 (a)5 marks $\mathrm{Cr_2O_7^{2-}}$
OR
Q.32 (b)5 marks $\mathrm{V_2O_5}$
Q.33 (a)5 marks $+\ \mathrm{CrO_3}\ \xrightarrow[273 - 283\ \mathrm{K}]{\mathrm{(CH_3CO)_2O}}$
OR
Q.33 (b)5 marks $2\mathrm{CH_3COOH} \xrightarrow[\text{heat}]{\mathrm{P_4O_{10}}}$

Section A

1 mark each

Q.11 mark $Which by-product is obtained in the manufacture of phenol from cumene ?$
Tap an option to check your answer.
Q.21 mark $Which reagents are required for one step conversion of chlorobenzene to toluene ?$
Tap an option to check your answer.
Q.31 mark $\mathrm{[Fe(C_2O_4)_3]^{3-}}$
Tap an option to check your answer.
Q.41 mark $Which of the following complexes shows geometrical isomerism ?$
Tap an option to check your answer.
Q.51 mark $Which of the following does not show variable oxidation state ?$
Tap an option to check your answer.
Q.61 mark $The reagent that can be used to convert benzenediazonium chloride to benzene is :$
Tap an option to check your answer.
Q.71 mark $\mathrm{HNO_2}$
Tap an option to check your answer.
Q.81 mark $A solution of acetone in chloroform :$
Tap an option to check your answer.
Q.91 mark $\mathrm{K_f}$
Tap an option to check your answer.
Q.101 mark $A galvanic cell can behave like an electrolytic cell when$
Tap an option to check your answer.
Q.111 mark $The value of rate constant for a pseudo first order reaction :$
Tap an option to check your answer.
Q.121 mark $Furanose ring of fructose is formed due to reaction between :$
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 $Assertion (A) : Actinoids show wide range of oxidation states. Reason (R) : This is due to comparable energies of 5f, 6d and 7s orbitals.$
Tap an option to check your answer.
Q.141 mark $Assertion (A) : Order of the reaction can be zero or fractional. Reason (R) : We cannot determine order from balanced chemical equation.$
Tap an option to check your answer.
Q.151 mark $\mathrm{(C_2H_5)_2NH}$
Tap an option to check your answer.
Q.161 mark $Assertion (A) : Phenol is less acidic than alcohol. Reason (R) : Phenoxide ion is more stable than alkoxide ion.$
Tap an option to check your answer.

Section B

2 marks each

Q.172 marks $State Raoult’s law for a solution containing volatile components. Why is the vapour pressure of an aqueous solution of glucose lower than that of water ?$
Q.18 (a)2 marks $\mathrm{[CoCl_2(en)_2]SO_4}$
OR
Q.18 (b)2 marks $Differentiate between : (i) Double salt and Complex compound (ii) Didentate ligand and Ambidentate ligand$
Q.192 marks $Observe the graph in the given figure and answer the following questions : (a) Predict the order of reaction. (b) What is the slope of the curve ?$
Q.202 marks $How do you explain the following ? (a) Presence of an aldehydic group in glucose. (b) Presence of five - OH groups in glucose.$
Q.212 marks $\xrightarrow{\mathrm{SOCl_2}}$

Section C

3 marks each

Q.223 marks $p$
Q.233 marks $\mathrm{C_4H_5N}$
Q.243 marks $\mathrm{S_N}1$
Q.253 marks $24{\cdot}8$
Q.26 (a)3 marks $\mathrm{[FeF_6]^{3-}}$
OR
Q.26 (b)3 marks $\mathrm{[Ti(H_2O)_6]^{3+}}$
Q.273 marks $Give reasons for the following : (a) The pH of aqueous NaCl increases when it is electrolysed. (b) Unlike dry cell, mercury cell has a constant cell potential through its lifetime. (c) Conductivity of solution decreases with dilution.$

Q.283 marks

\longrightarrow

Experiment	[A] / mol $\mathrm{L^{-1}}$	[B] / mol $\mathrm{L^{-1}}$	Initial Rate/mol $\mathrm{L^{-1}\,min^{-1}}$
1	$0{\cdot}01$	$0{\cdot}01$	$5 \times 10^{-3}$
2	$0{\cdot}02$	$0{\cdot}01$	$1 \times 10^{-2}$
3	$0{\cdot}01$	$0{\cdot}02$	$5 \times 10^{-3}$

Section D

The $\alpha$ -amino acids are the building blocks of proteins. All $\alpha$ -amino acids exist as zwitter ion due to which they show amphoteric behaviour. All amino acids are joined through peptide bond. Proteins are broadly classified as globular proteins and fibrous proteins. Globular proteins are water soluble, whereas fibrous proteins are not. The complete structure of protein is discussed at four different levels i.e. primary, secondary, tertiary and quaternary structures. Protein loses its biological activity in denatured form.
Q.29 (a)2 marks $Define the following : (i) Peptide linkage (ii) Denatured protein$
Q.29 (b)1 mark $Why do amino acids show amphoteric behaviour ?$
Q.29 (c) (i)1 mark $How can you differentiate between Fibrous protein and Globular protein ?$
OR
Q.29 (c) (ii)1 mark $Write the names of two different secondary structures of proteins.$
Alcohols undergo a number of reactions involving the cleavage of C – OH bond. However, phenols do not undergo reactions involving the cleavage of C – OH bond. Alcohols are weaker acids than water. Alcohols react with halogen acids to form the corresponding haloalkanes. Phenols are stronger acids than alcohols. A characteristic feature of phenols is that they undergo electrophilic substitution reactions such as halogenation, nitration, etc. Since – OH group is a strong activating group, phenol gives trisubstituted products during halogenation, nitration, etc.
Q.30 (a)2 marks $\mathrm{Br_2}$
Q.30 (b) (i)1 mark $\mathrm{CH_3^{\oplus}}$
OR
Q.30 (b) (ii)1 mark $Why do phenols not undergo reactions involving cleavage of C - OH bond ?$
Q.30 (c)1 mark $\mathrm{ZnCl_2}$

Section E

5 marks each

Q.31 (a)5 marks $+\ \mathrm{CrO_3}\ \xrightarrow[273 - 283\ \mathrm{K}]{\mathrm{(CH_3CO)_2O}}$
OR
Q.31 (b)5 marks $2\mathrm{CH_3COOH} \xrightarrow[\text{heat}]{\mathrm{P_4O_{10}}}$
Q.32 (a)5 marks $\mathrm{E_{cell}}$
OR
Q.32 (b)5 marks $0{\cdot}001$
Q.33 (a)5 marks $\mathrm{Cr_2O_7^{2-}}$
OR
Q.33 (b)5 marks $\mathrm{V_2O_5}$

Section A

1 mark each

Q.11 mark $\mathrm{H_2SO_4}$
Tap an option to check your answer.
Q.21 mark $Which reagents are required for one step conversion of Chlorobenzene to Diphenyl ?$
Tap an option to check your answer.
Q.31 mark $Which of the following complexes show linkage isomerism ?$
Tap an option to check your answer.
Q.41 mark $Which of the following transition metals has the highest melting point ?$
Tap an option to check your answer.
Q.51 mark $\mathrm{K_f}$
Tap an option to check your answer.
Q.61 mark $The reagent that can be used to convert benzenediazonium chloride to benzonitrile is :$
Tap an option to check your answer.
Q.71 mark $The strongest base in aqueous solution among the following amines is :$
Tap an option to check your answer.
Q.81 mark $On mixing 30 mL of acetone with 20 mL of chloroform, the total volume of solution is :$
Tap an option to check your answer.
Q.91 mark $We cannot measure the resistance of an ionic solution using DC because :$
Tap an option to check your answer.
Q.101 mark $\mathrm{[Co(en)_3]Cl_3}$
Tap an option to check your answer.
Q.111 mark $\mathrm{k = Ae^{-E_a/RT}}$
Tap an option to check your answer.
Q.121 mark $\alpha$
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 $Assertion (A) : Actinoid contraction is greater from element to element than lanthanoid contraction. Reason (R) : Actinoids show wide range of oxidation states.$
Tap an option to check your answer.
Q.141 mark $Assertion (A) : Molecularity of reaction is determined experimentally. Reason (R) : Molecularity is applicable only for an elementary reaction and not for a complex reaction.$
Tap an option to check your answer.
Q.151 mark $\mathrm{(C_2H_5)_2NH}$
Tap an option to check your answer.
Q.161 mark $Assertion (A) : The bond angle C - O - C in ethers is slightly greater than tetrahedral angle. Reason (R) : This is because of the repulsive interaction between the two bulky alkyl groups.$
Tap an option to check your answer.

Section B

2 marks each

Q.172 marks $Define osmotic pressure. Why is measurement of osmotic pressure method preferred for the determination of molar masses of macromolecules such as proteins and polymers ?$
Q.182 marks $How do you explain the following ? (a) Presence of an aldehydic group in glucose. (b) Presence of five - OH groups in glucose.$
Q.192 marks $\xrightarrow{\mathrm{Br_2},\ \text{heat}}$
Q.202 marks $Observe the graph in the given figure and answer the following questions : (a) Predict the order of reaction. (b) What is the slope of the curve ?$
Q.21 (a)2 marks $\mathrm{[CoCl_2(en)_2]SO_4}$
OR
Q.21 (b)2 marks $Differentiate between : (i) Double salt and Complex compound (ii) Didentate ligand and Ambidentate ligand$

Section C

3 marks each

Q.223 marks $How can you obtain the following ? (a) Aniline from ammonium benzoate (b) Benzene diazonium chloride from nitrobenzene (c) 2,4,6-tribromoaniline from aniline$
Q.233 marks $Give reasons for the following : (a) The pH of aqueous NaCl increases when it is electrolysed. (b) Unlike dry cell, mercury cell has a constant cell potential through its lifetime. (c) Conductivity of solution decreases with dilution.$

Q.243 marks

\longrightarrow

Q.253 marks $\mathrm{S_N}1$
Q.263 marks $\mathrm{C_4H_5N}$
Q.27 (a)3 marks $\mathrm{[FeF_6]^{3-}}$
OR
Q.27 (b)3 marks $\mathrm{[Ti(H_2O)_6]^{3+}}$
Q.283 marks $24{\cdot}8$

Experiment	[A] / mol $\mathrm{L^{-1}}$	[B] / mol $\mathrm{L^{-1}}$	Initial Rate/mol $\mathrm{L^{-1}\,min^{-1}}$
1	$0{\cdot}01$	$0{\cdot}01$	$5 \times 10^{-3}$
2	$0{\cdot}02$	$0{\cdot}01$	$1 \times 10^{-2}$
3	$0{\cdot}01$	$0{\cdot}02$	$5 \times 10^{-3}$

Section D

Alcohols undergo a number of reactions involving the cleavage of C – OH bond. However, phenols do not undergo reactions involving the cleavage of C – OH bond. Alcohols are weaker acids than water. Alcohols react with halogen acids to form the corresponding haloalkanes. Phenols are stronger acids than alcohols. A characteristic feature of phenols is that they undergo electrophilic substitution reactions such as halogenation, nitration, etc. Since – OH group is a strong activating group, phenol gives trisubstituted products during halogenation, nitration, etc.
Q.29 (a)2 marks $\mathrm{Br_2}$
Q.29 (b) (i)1 mark $\mathrm{CH_3^{\oplus}}$
OR
Q.29 (b) (ii)1 mark $Why do phenols not undergo reactions involving cleavage of C - OH bond ?$
Q.29 (c)1 mark $\mathrm{ZnCl_2}$
The $\alpha$ -amino acids are the building blocks of proteins. All $\alpha$ -amino acids exist as zwitter ion due to which they show amphoteric behaviour. All amino acids are joined through peptide bond. Proteins are broadly classified as globular proteins and fibrous proteins. Globular proteins are water soluble, whereas fibrous proteins are not. The complete structure of protein is discussed at four different levels i.e. primary, secondary, tertiary and quaternary structures. Protein loses its biological activity in denatured form.
Q.30 (a)2 marks $Define the following : (i) Peptide linkage (ii) Denatured protein$
Q.30 (b)1 mark $Why do amino acids show amphoteric behaviour ?$
Q.30 (c) (i)1 mark $How can you differentiate between Fibrous protein and Globular protein ?$
OR
Q.30 (c) (ii)1 mark $Write the names of two different secondary structures of proteins.$

Section E

5 marks each

Q.31 (a)5 marks $\mathrm{Cr_2O_7^{2-}}$
OR
Q.31 (b)5 marks $\mathrm{V_2O_5}$
Q.32 (a)5 marks $+\ \mathrm{CrO_3}\ \xrightarrow[273 - 283\ \mathrm{K}]{\mathrm{(CH_3CO)_2O}}$
OR
Q.32 (b)5 marks $2\mathrm{CH_3COOH} \xrightarrow[\text{heat}]{\mathrm{P_4O_{10}}}$
Q.33 (a)5 marks $\mathrm{E_{cell}}$
OR
Q.33 (b)5 marks $0{\cdot}001$