CBSE Class 12 Chemistry 2025 question paper (56/5)

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 $The role of a catalyst is to change :$
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Q.21 mark $Which of the following molecules is chiral in nature ?$
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Q.31 mark $\mathrm{CH_3CH_2OH}$
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Q.41 mark $\mathrm{CH_3-CH_2-N(CH_3)-CH_2-CH_2-CH_3}$
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Q.51 mark $[\mathrm{R}]$
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Q.61 mark $The treatment of ethyl bromide with alcoholic silver nitrite gives :$
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Q.71 mark $Which of the following aqueous solutions will have the highest freezing point ?$
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Q.81 mark $Which of the following aldehydes will undergo Cannizzaro reaction ?$
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Q.91 mark $\mathrm{Cu^{+}}$
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Q.101 mark $\mathrm{CH_3CH_2CHO}$
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Q.111 mark $Match the type of cell given in Column I with their use given in Column II. Column I Column II i. Lead storage cell a. Wall clock ii. Mercury cell b. Apollo Space Programme iii. Dry cell c. Wrist watch iv. Fuel cell d. Inverter$
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Q.121 mark $While doing qualitative analysis in chemistry lab, Abhishek added yellow coloured potassium chromate solution into a test tube. He was surprised to see the colour of the solution changing immediately to orange. He realised that the test tube was not clean and contained a few drops of some liquid. Which of the following substances will be the most likely liquid to be present in the test tube before adding potassium chromate solution ?$
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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 $Assertion (A) : For measuring resistance of an ionic solution an AC source is used. Reason (R) : Concentration of ionic solution will change if DC source is used.$
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Q.141 mark $(\mathrm{K_H})$
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Q.151 mark $Assertion (A) : The solubility of aldehydes and ketones in water decreases with increase in size of the alkyl group. Reason (R) : Aldehydes and ketones have dipole-dipole interaction.$
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Q.161 mark $\mathrm{RI} > \mathrm{RBr} > \mathrm{RCl} > \mathrm{RF}$
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Column I	Column II
i. Lead storage cell	a. Wall clock
ii. Mercury cell	b. Apollo Space Programme
iii. Dry cell	c. Wrist watch
iv. Fuel cell	d. Inverter

Section B

2 marks each

Q.17 (a)2 marks $\mathrm{CaCl_2}$
OR
Q.17 (b)2 marks $Liquids 'X' and 'Y' form an ideal solution. The vapour pressure of pure 'X' and pure 'Y' are 120 mm Hg and 160 mm Hg respectively. Calculate the vapour pressure of the solution containing equal moles of 'X' and 'Y'.$

Q.182 marks

298{\cdot}15

Q.192 marks $2\mathrm{HI} \rightarrow \mathrm{H_2} + \mathrm{I_2}$
Q.202 marks $Explain the mechanism of acid catalysed hydration of ethene.$
Q.212 marks $(a) How can acetaldehyde be prepared from acetyl chloride ? (b) Propanal is more reactive than propanone towards nucleophilic addition reaction. Give reason.$

Concentration of KCl solution in mol / L	Conductivity at $298{\cdot}15$ K in S $\mathrm{cm^{-1}}$	Molar Conductivity at $298{\cdot}15$ K in S $\mathrm{cm^{2}\,mol^{-1}}$
$1{\cdot}000$	$0{\cdot}1113$	$111{\cdot}3$
$0{\cdot}100$	$0{\cdot}0129$	$129{\cdot}0$
$0{\cdot}010$	$0{\cdot}00141$	$141{\cdot}0$

Section C

3 marks each

Q.22 (a)3 marks $20{\cdot}2$
OR
Q.22 (b)3 marks $0{\cdot}5\%$

Q.233 marks

\mathrm{A} + \mathrm{B} \rightarrow

Q.243 marks $\mathrm{d^4}$
Q.253 marks $\mathrm{C-Cl}$
Q.263 marks $(a) Arrange the following compounds in the increasing order of their acidic strength : 3,5-dinitrophenol, 4-methylphenol, phenol, 2,4,6-trinitrophenol (b) What happens when : (write equations) (i) Phenol is distilled with Zn dust ? (ii) Anisole is treated with HBr ?$
Q.273 marks $\mathrm{C_8H_8O}$
Q.283 marks $\alpha$

Sl. No.	$\mathrm{[A]/mol\ L^{-1}}$	$\mathrm{[B]/mol\ L^{-1}}$	Initial rate $\mathrm{/mol\ L^{-1}\,s^{-1}}$
1	$0{\cdot}1$	$0{\cdot}1$	$0{\cdot}05$
2	$0{\cdot}2$	$0{\cdot}1$	$0{\cdot}10$
3	$0{\cdot}1$	$0{\cdot}2$	$0{\cdot}05$

Section D

Carbohydrates are polyhydroxy aldehydes or ketones that represent enormous structural diversity in terms of the arrangement of atoms in space, resulting in hundreds of stereoisomers. Although the chemical properties of most stereoisomers may not be very different, their metabolic rate and utilization in biological systems is significantly different and known to influence the overall carbohydrate metabolism. Structural variants, which arise due to a different arrangement of atoms in three-dimensional space are known as stereoisomers. The number of stereoisomers can be theoretically estimated by using the formula 2n, where 'n' is the number of stereocenters or asymmetric (chiral) carbon atoms in a molecule. Out of these stereoisomers, there are some structures, which are mirror images of each other, and they are referred to as enantiomers.
Q.29 (a)2 marks $Give chemical reactions to show the presence of an aldehydic group and straight chain in glucose.$
Q.29 (b) (i)1 mark $Define anomers.$
OR
Q.29 (b) (ii) OR1 mark $\beta$
Q.29 (c)1 mark $Sucrose is known as invert sugar. Explain.$
Werner's coordination theory in 1893 was the first attempt to explain the bonding in coordination complexes. It must be remembered that this theory was put forward before the electron had been discovered by J.J. Thomson in 1897, and before the electronic theory of valency. Werner did not have any of the modern instrumental techniques and all his studies were made using simple experimental techniques. Werner was able to explain the nature of bonding in complexes and he concluded that in complexes, the metal shows two different sorts of valency : primary and secondary. Primary valences are normally ionisable whereas secondary valences are non ionisable.
Q.30 (a)2 marks $\mathrm{CrCl_3 \cdot 4H_2O}$
Q.30 (b)1 mark $What is the difference between a complex and a double salt ?$
Q.30 (c) (i)1 mark $\mathrm{[Cr(NH_3)_3Cl_3]}$
OR
Q.30 (c) (ii) OR1 mark $Write two differences between primary and secondary valences in coordination compounds.$

Section E

5 marks each

Q.31 (a)5 marks $\mathrm{Cr^{3+}} + 3\mathrm{e^{-}} \rightarrow \mathrm{Cr\,(s)}$
OR
Q.31 (b)5 marks $\Lambda^{\circ}_{\mathrm{m}}\,\mathrm{NH_4Cl}$
Q.32 (a)5 marks $\mathrm{C_2H_7N}$
OR
Q.32 (b)5 marks $\mathrm{CHCl_3}$
Q.33 (a)5 marks $\mathrm{Fe^{2+}}$
OR
Q.33 (b)5 marks $(i) While studying the periodic properties, Arti came across an abnormal behaviour in the atomic size of Hf. She found that, even though Hf is placed below Zr in the same group, both have almost similar atomic sizes. (I) Which phenomenon is responsible for the above behaviour ? Define it. (II) Mention any other consequence of the above phenomenon. (ii) Give reasons for the following : (I) Transition metals exhibit catalytic properties. (II) Transition metals have high enthalpy of atomisation. (III) Sc is a transition element, while Zn is not.$

Section A

1 mark each

Q.11 mark $While doing qualitative analysis in chemistry lab, Abhishek added yellow coloured potassium chromate solution into a test tube. He was surprised to see the colour of the solution changing immediately to orange. He realised that the test tube was not clean and contained a few drops of some liquid. Which of the following substances will be the most likely liquid to be present in the test tube before adding potassium chromate solution ?$
Tap an option to check your answer.
Q.21 mark $The role of a catalyst is to change :$
Tap an option to check your answer.
Q.31 mark $Match the type of cell given in Column I with their use given in Column II. Column I Column II i. Lead storage cell a. Wall clock ii. Mercury cell b. Apollo Space Programme iii. Dry cell c. Wrist watch iv. Fuel cell d. Inverter$
Tap an option to check your answer.
Q.41 mark $\mathrm{CH_3CH_2OH}$
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Q.51 mark $\mathrm{CH_3-CH_2-N(CH_3)-CH_2-CH_2-CH_3}$
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Q.61 mark $[\mathrm{R}]$
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Q.71 mark $The treatment of ethyl bromide with alcoholic silver nitrite gives :$
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Q.81 mark $Which of the following aqueous solutions will have the highest freezing point ?$
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Q.91 mark $Which of the following aldehydes will undergo Cannizzaro reaction ?$
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Q.101 mark $\mathrm{Cu^{+}}$
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Q.111 mark $Which of the following molecules is chiral in nature ?$
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Q.121 mark $\mathrm{CH_3CH_2CHO}$
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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 $\mathrm{RI} > \mathrm{RBr} > \mathrm{RCl} > \mathrm{RF}$
Tap an option to check your answer.
Q.141 mark $Assertion (A) : For measuring resistance of an ionic solution an AC source is used. Reason (R) : Concentration of ionic solution will change if DC source is used.$
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Q.151 mark $(\mathrm{K_H})$
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Q.161 mark $Assertion (A) : The solubility of aldehydes and ketones in water decreases with increase in size of the alkyl group. Reason (R) : Aldehydes and ketones have dipole-dipole interaction.$
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Column I	Column II
i. Lead storage cell	a. Wall clock
ii. Mercury cell	b. Apollo Space Programme
iii. Dry cell	c. Wrist watch
iv. Fuel cell	d. Inverter

Section B

2 marks each

Q.172 marks

298{\cdot}15

Q.18 (a)2 marks $\mathrm{CaCl_2}$
OR
Q.18 (b)2 marks $Liquids 'X' and 'Y' form an ideal solution. The vapour pressure of pure 'X' and pure 'Y' are 120 mm Hg and 160 mm Hg respectively. Calculate the vapour pressure of the solution containing equal moles of 'X' and 'Y'.$
Q.192 marks $4{\cdot}5 \times 10^{-5}$
Q.202 marks $\mathrm{H_2SO_4}$
Q.212 marks $(a) Give a simple chemical test to distinguish between 3-pentanone and 2-pentanone. (b) Write an equation for Clemmensen reduction.$

Concentration of KCl solution in mol / L	Conductivity at $298{\cdot}15$ K in S $\mathrm{cm^{-1}}$	Molar Conductivity at $298{\cdot}15$ K in S $\mathrm{cm^{2}\,mol^{-1}}$
$1{\cdot}000$	$0{\cdot}1113$	$111{\cdot}3$
$0{\cdot}100$	$0{\cdot}0129$	$129{\cdot}0$
$0{\cdot}010$	$0{\cdot}00141$	$141{\cdot}0$

Section C

3 marks each

Q.223 marks

\mathrm{A} + \mathrm{B} \rightarrow

Q.23 (a)3 marks $20{\cdot}2$
OR
Q.23 (b)3 marks $0{\cdot}5\%$
Q.243 marks $[\mathrm{NiCl_4}]^{2-}$
Q.253 marks $\mathrm{CH_3-CH_2-CH(Br)-CH_3} + \text{alc. KOH} \longrightarrow$
Q.263 marks $o$
Q.273 marks $\mathrm{P} \xrightarrow{\mathrm{NH_3}} \mathrm{CH_3COO^-NH_4^+} \xrightarrow{\Delta} \mathrm{Q}$
Q.283 marks $(a) Name the vitamin whose deficiency causes pernicious anaemia. (b) Write any two differences between globular and fibrous proteins.$

Sl. No.	$\mathrm{[A]/mol\ L^{-1}}$	$\mathrm{[B]/mol\ L^{-1}}$	Initial rate $\mathrm{/mol\ L^{-1}\,s^{-1}}$
1	$0{\cdot}1$	$0{\cdot}1$	$0{\cdot}05$
2	$0{\cdot}2$	$0{\cdot}1$	$0{\cdot}10$
3	$0{\cdot}1$	$0{\cdot}2$	$0{\cdot}05$

Section D

Werner's coordination theory in 1893 was the first attempt to explain the bonding in coordination complexes. It must be remembered that this theory was put forward before the electron had been discovered by J.J. Thomson in 1897, and before the electronic theory of valency. Werner did not have any of the modern instrumental techniques and all his studies were made using simple experimental techniques. Werner was able to explain the nature of bonding in complexes and he concluded that in complexes, the metal shows two different sorts of valency : primary and secondary. Primary valences are normally ionisable whereas secondary valences are non ionisable.
Q.29 (a)2 marks $\mathrm{CrCl_3 \cdot 4H_2O}$
Q.29 (b)1 mark $What is the difference between a complex and a double salt ?$
Q.29 (c) (i)1 mark $\mathrm{[Cr(NH_3)_3Cl_3]}$
OR
Q.29 (c) (ii) OR1 mark $Write two differences between primary and secondary valences in coordination compounds.$
Carbohydrates are polyhydroxy aldehydes or ketones that represent enormous structural diversity in terms of the arrangement of atoms in space, resulting in hundreds of stereoisomers. Although the chemical properties of most stereoisomers may not be very different, their metabolic rate and utilization in biological systems is significantly different and known to influence the overall carbohydrate metabolism. Structural variants, which arise due to a different arrangement of atoms in three-dimensional space are known as stereoisomers. The number of stereoisomers can be theoretically estimated by using the formula 2n, where 'n' is the number of stereocenters or asymmetric (chiral) carbon atoms in a molecule. Out of these stereoisomers, there are some structures, which are mirror images of each other, and they are referred to as enantiomers.
Q.30 (a)2 marks $Give chemical reactions to show the presence of an aldehydic group and straight chain in glucose.$
Q.30 (b) (i)1 mark $Define anomers.$
OR
Q.30 (b) (ii) OR1 mark $\beta$
Q.30 (c)1 mark $Sucrose is known as invert sugar. Explain.$

Section E

5 marks each

Q.31 (a)5 marks $\mathrm{C_2H_7N}$
OR
Q.31 (b)5 marks $\mathrm{CHCl_3}$
Q.32 (a)5 marks $\mathrm{Fe^{2+}}$
OR
Q.32 (b)5 marks $(i) While studying the periodic properties, Arti came across an abnormal behaviour in the atomic size of Hf. She found that, even though Hf is placed below Zr in the same group, both have almost similar atomic sizes. (I) Which phenomenon is responsible for the above behaviour ? Define it. (II) Mention any other consequence of the above phenomenon. (ii) Give reasons for the following : (I) Transition metals exhibit catalytic properties. (II) Transition metals have high enthalpy of atomisation. (III) Sc is a transition element, while Zn is not.$
Q.33 (a)5 marks $\mathrm{Cr^{3+}} + 3\mathrm{e^{-}} \rightarrow \mathrm{Cr\,(s)}$
OR
Q.33 (b)5 marks $\Lambda^{\circ}_{\mathrm{m}}\,\mathrm{NH_4Cl}$

Section A

1 mark each

Q.11 mark $\mathrm{CH_3CH_2CHO}$
Tap an option to check your answer.
Q.21 mark $While doing qualitative analysis in chemistry lab, Abhishek added yellow coloured potassium chromate solution into a test tube. He was surprised to see the colour of the solution changing immediately to orange. He realised that the test tube was not clean and contained a few drops of some liquid. Which of the following substances will be the most likely liquid to be present in the test tube before adding potassium chromate solution ?$
Tap an option to check your answer.
Q.31 mark $The role of a catalyst is to change :$
Tap an option to check your answer.
Q.41 mark $Which of the following molecules is chiral in nature ?$
Tap an option to check your answer.
Q.51 mark $\mathrm{CH_3CH_2OH}$
Tap an option to check your answer.
Q.61 mark $\mathrm{CH_3-CH_2-N(CH_3)-CH_2-CH_2-CH_3}$
Tap an option to check your answer.
Q.71 mark $[\mathrm{R}]$
Tap an option to check your answer.
Q.81 mark $The treatment of ethyl bromide with alcoholic silver nitrite gives :$
Tap an option to check your answer.
Q.91 mark $Which of the following aqueous solutions will have the highest freezing point ?$
Tap an option to check your answer.
Q.101 mark $Which of the following aldehydes will undergo Cannizzaro reaction ?$
Tap an option to check your answer.
Q.111 mark $\mathrm{Cu^{+}}$
Tap an option to check your answer.
Q.121 mark $Match the type of cell given in Column I with their use given in Column II. Column I Column II i. Lead storage cell a. Wall clock ii. Mercury cell b. Apollo Space Programme iii. Dry cell c. Wrist watch iv. Fuel cell d. Inverter$
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 $Assertion (A) : The solubility of aldehydes and ketones in water decreases with increase in size of the alkyl group. Reason (R) : Aldehydes and ketones have dipole-dipole interaction.$
Tap an option to check your answer.
Q.141 mark $\mathrm{RI} > \mathrm{RBr} > \mathrm{RCl} > \mathrm{RF}$
Tap an option to check your answer.
Q.151 mark $Assertion (A) : For measuring resistance of an ionic solution an AC source is used. Reason (R) : Concentration of ionic solution will change if DC source is used.$
Tap an option to check your answer.
Q.161 mark $(\mathrm{K_H})$
Tap an option to check your answer.

Column I	Column II
i. Lead storage cell	a. Wall clock
ii. Mercury cell	b. Apollo Space Programme
iii. Dry cell	c. Wrist watch
iv. Fuel cell	d. Inverter

Section B

2 marks each

Q.17 (a)2 marks $\mathrm{CaCl_2}$
OR
Q.17 (b)2 marks $Liquids 'X' and 'Y' form an ideal solution. The vapour pressure of pure 'X' and pure 'Y' are 120 mm Hg and 160 mm Hg respectively. Calculate the vapour pressure of the solution containing equal moles of 'X' and 'Y'.$

Q.182 marks

298{\cdot}15

Q.192 marks $\mathrm{X} + \mathrm{Y} \rightarrow \mathrm{Z}$
Q.202 marks $\mathrm{H_2SO_4}$
Q.212 marks $(a) Carboxylic acid is more acidic than phenol. Give reason. (b) Give a chemical test to distinguish between benzaldehyde and acetophenone.$

Concentration of KCl solution in mol / L	Conductivity at $298{\cdot}15$ K in S $\mathrm{cm^{-1}}$	Molar Conductivity at $298{\cdot}15$ K in S $\mathrm{cm^{2}\,mol^{-1}}$
$1{\cdot}000$	$0{\cdot}1113$	$111{\cdot}3$
$0{\cdot}100$	$0{\cdot}0129$	$129{\cdot}0$
$0{\cdot}010$	$0{\cdot}00141$	$141{\cdot}0$

Section C

3 marks each

Q.22 (a)3 marks $20{\cdot}2$
OR
Q.22 (b)3 marks $0{\cdot}5\%$

Q.233 marks

\mathrm{A} + \mathrm{B} \rightarrow

Q.243 marks $\mathrm{[Ni(CN)_4]^{2-}}$
Q.253 marks $\mathrm{S_N}2$
Q.263 marks $(\mathrm{CH_3})_3\,\mathrm{C} - \mathrm{O} - \mathrm{CH_3} + \mathrm{HI} \rightarrow$
Q.273 marks $\mathrm{CH_3CHO} + \mathrm{NH_2CONHNH_2} \rightarrow$
Q.283 marks $(a) Name the vitamin which is responsible for coagulation of blood. (b) What is meant by denaturation of protein ? Give an example.$

Sl. No.	$\mathrm{[A]/mol\ L^{-1}}$	$\mathrm{[B]/mol\ L^{-1}}$	Initial rate $\mathrm{/mol\ L^{-1}\,s^{-1}}$
1	$0{\cdot}1$	$0{\cdot}1$	$0{\cdot}05$
2	$0{\cdot}2$	$0{\cdot}1$	$0{\cdot}10$
3	$0{\cdot}1$	$0{\cdot}2$	$0{\cdot}05$

Section D

Carbohydrates are polyhydroxy aldehydes or ketones that represent enormous structural diversity in terms of the arrangement of atoms in space, resulting in hundreds of stereoisomers. Although the chemical properties of most stereoisomers may not be very different, their metabolic rate and utilization in biological systems is significantly different and known to influence the overall carbohydrate metabolism. Structural variants, which arise due to a different arrangement of atoms in three-dimensional space are known as stereoisomers. The number of stereoisomers can be theoretically estimated by using the formula 2n, where 'n' is the number of stereocenters or asymmetric (chiral) carbon atoms in a molecule. Out of these stereoisomers, there are some structures, which are mirror images of each other, and they are referred to as enantiomers.
Q.29 (a)2 marks $Give chemical reactions to show the presence of an aldehydic group and straight chain in glucose.$
Q.29 (b) (i)1 mark $Define anomers.$
OR
Q.29 (b) (ii)1 mark $\beta$
Q.29 (c)1 mark $Sucrose is known as invert sugar. Explain.$
Werner's coordination theory in 1893 was the first attempt to explain the bonding in coordination complexes. It must be remembered that this theory was put forward before the electron had been discovered by J.J. Thomson in 1897, and before the electronic theory of valency. Werner did not have any of the modern instrumental techniques and all his studies were made using simple experimental techniques. Werner was able to explain the nature of bonding in complexes and he concluded that in complexes, the metal shows two different sorts of valency : primary and secondary. Primary valences are normally ionisable whereas secondary valences are non ionisable.
Q.30 (a)2 marks $\mathrm{CrCl_3 \cdot 4H_2O}$
Q.30 (b)1 mark $What is the difference between a complex and a double salt ?$
Q.30 (c) (i)1 mark $\mathrm{[Cr(NH_3)_3Cl_3]}$
OR
Q.30 (c) (ii)1 mark $Write two differences between primary and secondary valences in coordination compounds.$

Section E

5 marks each

Q.31 (a)5 marks $\mathrm{Fe^{2+}}$
OR
Q.31 (b)5 marks $(i) While studying the periodic properties, Arti came across an abnormal behaviour in the atomic size of Hf. She found that, even though Hf is placed below Zr in the same group, both have almost similar atomic sizes. (I) Which phenomenon is responsible for the above behaviour ? Define it. (II) Mention any other consequence of the above phenomenon. (ii) Give reasons for the following : (I) Transition metals exhibit catalytic properties. (II) Transition metals have high enthalpy of atomisation. (III) Sc is a transition element, while Zn is not.$
Q.32 (a)5 marks $\mathrm{Cr^{3+}} + 3\mathrm{e^{-}} \rightarrow \mathrm{Cr\,(s)}$
OR
Q.32 (b)5 marks $\Lambda^{\circ}_{\mathrm{m}}\,\mathrm{NH_4Cl}$
Q.33 (a)5 marks $\mathrm{C_2H_7N}$
OR
Q.33 (b)5 marks $\mathrm{CHCl_3}$