CBSE Class 12 Chemistry 2025 question paper (56/4)

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 $\mathrm{2Cu^{+}\,(aq) + Zn\,(s) \rightarrow 2Cu\,(s) + Zn^{2+}\,(aq)}$
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Q.21 mark $\mathrm{Fe^{3+}}$
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Q.31 mark $Hoffmann Bromamide degradation reaction is given by :$
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Q.41 mark $In the Haworth structure of the following carbohydrate, various carbon atoms have been numbered. The anomeric carbon is numbered as :$
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Q.51 mark $\mathrm{K_H}$
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Q.61 mark $Out of the following statements, the incorrect statement is :$
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Q.71 mark $Out of 2-Bromobutane, 1-Bromobutane, 2-Bromopropane and 1-Bromopropane, the molecule which is chiral in nature is :$
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Q.81 mark $\xrightarrow[\mathrm{HCl},\ 0-5^{\circ}\mathrm{C}]{\mathrm{NaNO_2}}$
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Q.91 mark $\mathrm{I^{-}}$
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Q.101 mark $Polyhalogen compounds have wide application in industries and agriculture. DDT is also a very important polyhalogen compound. It is a :$
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Q.111 mark $\mathrm{MnO_4^{-}}$
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Q.121 mark $\mathrm{H_2SO_4}$
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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 $\mathrm{H_2}$
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Q.141 mark $Assertion (A) : Cuprous salts are diamagnetic. Reason (R) : Cuprous ion has completely filled 3d-orbitals.$
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Q.151 mark $Assertion (A) : n-Butyl chloride has higher boiling point than n-Butyl bromide. Reason (R) : C - Cl bond is more polar than C - Br bond.$
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Q.161 mark $Assertion (A) : Acetanilide is less basic than aniline. Reason (R) : Acetylation of aniline results in decrease of electron density on nitrogen.$
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Section B

2 marks each

Q.17 (a)2 marks $0{\cdot}40$
OR
Q.17 (b)2 marks $\mathrm{H_2\,(g)}$
Q.182 marks $\mathrm{PtCl_4 \cdot 2KCl}$
Q.192 marks $Define fuel cell. Give two advantages of fuel cell over ordinary cell.$
Q.202 marks $\xrightarrow{\mathrm{NaBH_4}}$
Q.212 marks $What is meant by essential amino acids ? Why are amino acids amphoteric in nature ?$

Time / Hours	[A]/M
0	$0{\cdot}40$
1	$0{\cdot}20$
2	$0{\cdot}10$
3	$0{\cdot}05$

Section C

3 marks each

Q.22 (a)3 marks $\overline{\mathrm{O}}\mathrm{H}$
OR
Q.22 (b)3 marks $\mathrm{CH_3CH=CH_2} \xrightarrow[\mathrm{Peroxide}]{\mathrm{HBr}}$
Q.233 marks $25^{\circ}\mathrm{C}$
Q.243 marks $(\mathrm{d^4})$
Q.253 marks $27^{\circ}\mathrm{C}$
Q.263 marks $\mathrm{pK_b}$
Q.273 marks $\mathrm{C_8H_8O}$
Q.283 marks $(a) Can sodium ethoxide and t-butyl chloride be used for the preparation of t-butyl ethyl ether ? Give suitable explanation. Justify your answer by suggesting the appropriate starting material required for preparation of t-butyl ethyl ether. (b) Give the IUPAC name of above mentioned ether.$

Section D

According to the generally accepted definition of the ideal solution there are equal interaction forces acting between molecules belonging to the same or different species. (This is equivalent to the statement that the activity of the components equals the concentration.) Strictly speaking, this condition is fulfilled only in exceptional cases for mixtures (optical isomers, isotopic mixtures of an element, hydrocarbon mixtures). It is still usual to talk about ideal solutions as limiting cases in reality since very dilute solutions behave ideally with respect to the solvent. This view is further supported by the fact that Raoult's law empirically found for describing the behaviour of the solvent in dilute solutions can be deduced thermodynamically via the assumption of ideal behaviour of the solvent.
Q.29 (a)2 marks $Give one example of miscible liquid pair which shows negative deviation from Raoult's law. What is the reason for such deviation ?$
Q.29 (b) (i)1 mark $State Raoult's law for a solution containing volatile components.$
OR
Q.29 (b) (ii)1 mark $Raoult's law is a special case of Henry's law. Comment.$
Q.29 (c)1 mark $Write two characteristics of an ideal solution.$
Ribose and 2-deoxyribose have an important role in biology. Among the most important derivatives are those with phosphate groups attached at the 5 position. Mono-, di- and tri-phosphate forms are important, as well as 3-5 cyclic monophosphates. Purines and pyrimidines form an important class of compounds with ribose and deoxyribose. When these purine and pyrimidine derivatives are coupled to a ribose sugar, they are called nucleosides.
Q.30 (a)2 marks $What products would be formed when DNA is hydrolysed ? How is DNA different from RNA with reference to a structure ?$
Q.30 (b)1 mark $Differentiate between nucleotide and nucleoside.$
Q.30 (c) (i)1 mark $Mention two important functions of nucleic acid.$
OR
Q.30 (c) (ii)1 mark $Name the linkage which joins two nucleotides. Name the base that is found in nucleotide of RNA but not in DNA.$

Section E

5 marks each

Q.31 (a)5 marks $\xrightarrow{\mathrm{H_2NCONH\!-\!NH_2}}$
OR
Q.31 (b)5 marks $\xrightarrow[\mathrm{(ii)\ H_3O^{+}}]{\mathrm{(i)\ KMnO_4,\ KOH}}$
Q.32 (a)5 marks $\mathrm{[Ni(CO)_4]}$
OR
Q.32 (b)5 marks $\mathrm{[Co(NH_3)_6]\,[Cr(CN)_6]}$
Q.33 (a)5 marks $\mathrm{N_2O_5}$
OR
Q.33 (b)5 marks $(\mathrm{E_a})$

Section A

1 mark each

Q.11 mark $\mathrm{H_2SO_4}$
Tap an option to check your answer.
Q.21 mark $Polyhalogen compounds have wide application in industries and agriculture. DDT is also a very important polyhalogen compound. It is a :$
Tap an option to check your answer.
Q.31 mark $\mathrm{I^{-}}$
Tap an option to check your answer.
Q.41 mark $\xrightarrow[\mathrm{HCl},\ 0-5^{\circ}\mathrm{C}]{\mathrm{NaNO_2}}$
Tap an option to check your answer.
Q.51 mark $Out of 2-Bromobutane, 1-Bromobutane, 2-Bromopropane and 1-Bromopropane, the molecule which is chiral in nature is :$
Tap an option to check your answer.
Q.61 mark $In the Haworth structure of the following carbohydrate, various carbon atoms have been numbered. The anomeric carbon is numbered as :$
Tap an option to check your answer.
Q.71 mark $\mathrm{K_H}$
Tap an option to check your answer.
Q.81 mark $Out of the following statements, the incorrect statement is :$
Tap an option to check your answer.
Q.91 mark $\mathrm{2Ag^{+}\,(aq) + Mg\,(s) \rightarrow 2Ag\,(s) + Mg^{2+}\,(aq)}$
Tap an option to check your answer.
Q.101 mark $\mathrm{Ti^{3+}}$
Tap an option to check your answer.
Q.111 mark $Hoffmann Bromamide degradation reaction is given by :$
Tap an option to check your answer.
Q.121 mark $\mathrm{H_2O}$
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 $Assertion (A) : Cuprous salts are diamagnetic. Reason (R) : In cuprous ion, 3d-orbitals are partially filled.$
Tap an option to check your answer.
Q.141 mark $Assertion (A) : Acetanilide is more basic than aniline. Reason (R) : Acetylation of aniline results in decrease of electron density on nitrogen.$
Tap an option to check your answer.
Q.151 mark $\mathrm{H_2}$
Tap an option to check your answer.
Q.161 mark $Assertion (A) : n-Butyl chloride has higher boiling point than n-Butyl bromide. Reason (R) : C - Cl bond is more polar than C - Br bond.$
Tap an option to check your answer.

Section B

2 marks each

Q.172 marks $What is meant by essential amino acids ? Why are amino acids amphoteric in nature ?$
Q.18 (a)2 marks $0{\cdot}40$
OR
Q.18 (b)2 marks $\mathrm{H_2\,(g)}$
Q.192 marks $\mathrm{PtCl_4 \cdot 2KCl}$
Q.202 marks $Define fuel cell. Give two advantages of fuel cell over ordinary cell.$
Q.212 marks $\mathrm{6\,R_3C\!-\!OH + 2Al \longrightarrow}$

Time / Hours	[A]/M
0	$0{\cdot}40$
1	$0{\cdot}20$
2	$0{\cdot}10$
3	$0{\cdot}05$

Section C

3 marks each

Q.223 marks $(a) Can sodium methoxide and t-butyl bromide be used for the preparation of t-butyl methyl ether. Give suitable reason. Justify your answer by suggesting the appropriate starting material if required for the preparation of t-butyl methyl ether. (b) Give the IUPAC name of above mentioned ether.$
Q.233 marks $\mathrm{pK_b}$
Q.243 marks $25^{\circ}\mathrm{C}$
Q.25 (a)3 marks $\overline{\mathrm{O}}\mathrm{H}$
OR
Q.25 (b)3 marks $\mathrm{CH_3CH=CH_2} \xrightarrow[\mathrm{Peroxide}]{\mathrm{HBr}}$
Q.263 marks $(\mathrm{d^4})$
Q.273 marks $27^{\circ}\mathrm{C}$
Q.283 marks $\mathrm{C_4H_8O}$

Section D

Ribose and 2-deoxyribose have an important role in biology. Among the most important derivatives are those with phosphate groups attached at the 5 position. Mono-, di- and tri-phosphate forms are important, as well as 3-5 cyclic monophosphates. Purines and pyrimidines form an important class of compounds with ribose and deoxyribose. When these purine and pyrimidine derivatives are coupled to a ribose sugar, they are called nucleosides.
Q.29 (a)2 marks $What products would be formed when DNA is hydrolysed ? How is DNA different from RNA with reference to a structure ?$
Q.29 (b)1 mark $Differentiate between nucleotide and nucleoside.$
Q.29 (c) (i)1 mark $Mention two important functions of nucleic acid.$
OR
Q.29 (c) (ii)1 mark $Name the linkage which joins two nucleotides. Name the base that is found in nucleotide of RNA but not in DNA.$
According to the generally accepted definition of the ideal solution there are equal interaction forces acting between molecules belonging to the same or different species. (This is equivalent to the statement that the activity of the components equals the concentration.) Strictly speaking, this condition is fulfilled only in exceptional cases for mixtures (optical isomers, isotopic mixtures of an element, hydrocarbon mixtures). It is still usual to talk about ideal solutions as limiting cases in reality since very dilute solutions behave ideally with respect to the solvent. This view is further supported by the fact that Raoult's law empirically found for describing the behaviour of the solvent in dilute solutions can be deduced thermodynamically via the assumption of ideal behaviour of the solvent.
Q.30 (a)2 marks $Give one example of miscible liquid pair which shows negative deviation from Raoult's law. What is the reason for such deviation ?$
Q.30 (b) (i)1 mark $State Raoult's law for a solution containing volatile components.$
OR
Q.30 (b) (ii)1 mark $Raoult's law is a special case of Henry's law. Comment.$
Q.30 (c)1 mark $Write two characteristics of an ideal solution.$

Section E

5 marks each

Q.31 (a)5 marks $\mathrm{N_2O_5}$
OR
Q.31 (b)5 marks $(\mathrm{E_a})$
Q.32 (a)5 marks $\xrightarrow{\mathrm{H_2NCONH\!-\!NH_2}}$
OR
Q.32 (b)5 marks $\xrightarrow[\mathrm{(ii)\ H_3O^{+}}]{\mathrm{(i)\ KMnO_4,\ KOH}}$
Q.33 (a)5 marks $\mathrm{[Ni(CO)_4]}$
OR
Q.33 (b)5 marks $\mathrm{[Co(NH_3)_6]\,[Cr(CN)_6]}$

Section A

1 mark each

Q.11 mark $\mathrm{2Cu^{+}\,(aq) + Zn\,(s) \rightarrow 2Cu\,(s) + Zn^{2+}\,(aq)}$
Tap an option to check your answer.
Q.21 mark $\mathrm{Ti^{3+}}$
Tap an option to check your answer.
Q.31 mark $Hoffmann Bromamide degradation reaction is given by :$
Tap an option to check your answer.
Q.41 mark $\mathrm{K_H}$
Tap an option to check your answer.
Q.51 mark $In the Haworth structure of the following carbohydrate, various carbon atoms have been numbered. The anomeric carbon is numbered as :$
Tap an option to check your answer.
Q.61 mark $Out of the following statements, the correct statement is :$
Tap an option to check your answer.
Q.71 mark $\xrightarrow[\mathrm{HCl},\ 0-5^{\circ}\mathrm{C}]{\mathrm{NaNO_2}}$
Tap an option to check your answer.
Q.81 mark $Out of 2-Bromobutane, 1-Bromobutane, 2-Bromopropane and 1-Bromopropane, the molecule which is chiral in nature is :$
Tap an option to check your answer.
Q.91 mark $Which of the following properties of transition metals enables them to behave as catalysts ?$
Tap an option to check your answer.
Q.101 mark $\mathrm{Fe_2O_3}$
Tap an option to check your answer.
Q.111 mark $\mathrm{H_2SO_4}$
Tap an option to check your answer.
Q.121 mark $Polyhalogen compounds have wide application in industries and agriculture. DDT is also a very important polyhalogen compound. It is a :$
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 $Assertion (A) : Acetanilide is less basic than aniline. Reason (R) : Acetylation of aniline results in decrease of electron density on nitrogen.$
Tap an option to check your answer.
Q.141 mark $Assertion (A) : Cuprous salts are diamagnetic. Reason (R) : Cuprous ion has completely filled 3d-orbitals.$
Tap an option to check your answer.
Q.151 mark $Assertion (A) : n-Butyl chloride has higher boiling point than n-Butyl bromide. Reason (R) : C - Cl bond is more polar than C - Br bond.$
Tap an option to check your answer.
Q.161 mark $\mathrm{H_2}$
Tap an option to check your answer.

Section B

2 marks each

Q.172 marks $What is meant by essential amino acids ? Why are amino acids amphoteric in nature ?$
Q.182 marks $\xrightarrow{\mathrm{NaBH_4}}$
Q.192 marks $Name and define the cell which was used for providing electric power in the Apollo space programme. Also write its one advantage.$
Q.202 marks $\mathrm{PdCl_2 \cdot 2KCl}$
Q.21 (a)2 marks $\mathrm{A_2\,(g)}$
OR
Q.21 (b)2 marks $0{\cdot}88$

Time / Hours	[A]/M
0	$0{\cdot}88$
1	$0{\cdot}44$
2	$0{\cdot}22$
3	$0{\cdot}11$

Section C

3 marks each

Q.223 marks $(\mathrm{d^4})$
Q.233 marks $\mathrm{C_8H_8O}$
Q.243 marks $\mathrm{pK_b}$
Q.25 (a)3 marks $\overline{\mathrm{O}}\mathrm{H}$
OR
Q.25 (b)3 marks $\mathrm{CH_3CH=CH_2} \xrightarrow[\mathrm{Peroxide}]{\mathrm{HBr}}$
Q.263 marks $(a) Can sodium propoxide and t-butyl chloride be used for the preparation of t-butyl propyl ether ? Give suitable explanation. Justify your answer by suggesting the appropriate starting material required for the preparation of t-butyl propyl ether. (b) Give the IUPAC name of the above mentioned ether.$
Q.273 marks $25^{\circ}\mathrm{C}$
Q.283 marks $25^{\circ}\mathrm{C}$

Section D

According to the generally accepted definition of the ideal solution there are equal interaction forces acting between molecules belonging to the same or different species. (This is equivalent to the statement that the activity of the components equals the concentration.) Strictly speaking, this condition is fulfilled only in exceptional cases for mixtures (optical isomers, isotopic mixtures of an element, hydrocarbon mixtures). It is still usual to talk about ideal solutions as limiting cases in reality since very dilute solutions behave ideally with respect to the solvent. This view is further supported by the fact that Raoult's law empirically found for describing the behaviour of the solvent in dilute solutions can be deduced thermodynamically via the assumption of ideal behaviour of the solvent.
Q.29 (a)2 marks $Give one example of miscible liquid pair which shows negative deviation from Raoult's law. What is the reason for such deviation ?$
Q.29 (b) (i)1 mark $State Raoult's law for a solution containing volatile components.$
OR
Q.29 (b) (ii)1 mark $Raoult's law is a special case of Henry's law. Comment.$
Q.29 (c)1 mark $Write two characteristics of an ideal solution.$
Ribose and 2-deoxyribose have an important role in biology. Among the most important derivatives are those with phosphate groups attached at the 5 position. Mono-, di- and tri-phosphate forms are important, as well as 3-5 cyclic monophosphates. Purines and pyrimidines form an important class of compounds with ribose and deoxyribose. When these purine and pyrimidine derivatives are coupled to a ribose sugar, they are called nucleosides.
Q.30 (a)2 marks $What products would be formed when DNA is hydrolysed ? How is DNA different from RNA with reference to a structure ?$
Q.30 (b)1 mark $Differentiate between nucleotide and nucleoside.$
Q.30 (c) (i)1 mark $Mention two important functions of nucleic acid.$
OR
Q.30 (c) (ii)1 mark $Name the linkage which joins two nucleotides. Name the base that is found in nucleotide of RNA but not in DNA.$

Section E

5 marks each

Q.31 (a)5 marks $\mathrm{[Ni(CO)_4]}$
OR
Q.31 (b)5 marks $\mathrm{[Co(NH_3)_6]\,[Cr(CN)_6]}$
Q.32 (a)5 marks $\mathrm{N_2O_5}$
OR
Q.32 (b)5 marks $(\mathrm{E_a})$
Q.33 (a)5 marks $\xrightarrow{\mathrm{H_2NCONH\!-\!NH_2}}$
OR
Q.33 (b)5 marks $\xrightarrow[\mathrm{(ii)\ H_3O^{+}}]{\mathrm{(i)\ KMnO_4,\ KOH}}$