CBSE Class 12 Chemistry 2026 Question Paper

Which of the following curve represents the first order reaction?

Which of the following solutions will have the lowest freezing point in water?

Which of the following is not a transition metal?

Which of the following represents the fraction of molecules with energies equal to or greater than Eₐ?

What will happen during the electrolysis of aqueous solution of CuCl₂ by using platinum electrodes?

Aspirin is obtained by acetylation of

The secondary valency of Co in the complex [Co(NH₃)₅(NO₂)]²⁺ is

At low temperature, phenol reacts with dil. HNO₃ to yield

Which of the following is 'not' true about enantiomers?

Aniline on direct nitration yields

Which of the following amines has lowest pKb value?

The deficiency of which of the following vitamins causes increased fragility of red blood cells and muscular weakness:

Assertion (A): It is not possible to separate the components of an azeotrope by fractional distillation. Reason (R): Components of an azeotrope have the same composition in liquid and vapour phase and boil at a constant temperature.

Assertion (A): The presence of –OH group in phenols directs the incoming group to meta position in the ring. Reason (R): –OH group in phenols activates the aromatic ring towards electrophilic substitution reaction.

Assertion (A): Actinoids show wide range of oxidation states. Reason (R): Actinoids are radioactive in nature.

Assertion (A): The pentaacetate of glucose does not react with H₂N – OH. Reason (R): It indicates the presence of free – CHO group in glucose.

What type of deviation from Raoult's law is shown by a mixture of phenol and aniline? Give reason. What will happen to the boiling point of the solution on mixing phenol and aniline?

Why are haloarenes less reactive towards nucleophilic substitution reaction? Give two reasons.

(a) Write IUPAC names of the following coordination compounds: (2 × 1) (i) [Ag(NH₃)₂] [Ag(CN)₂] (ii) K₃[Fe(C₂O₄)₃] OR (b) (i) Give a chemical test to show that [Co(NH₃)₅SO₄]Cl and [Co(NH₃)₅Cl]SO₄ are ionisation isomers. (2 × 1) (ii) What is meant by the 'Chelate effect'? Give an example.

Differentiate between the following: (2 × 1) (i) Peptide linkage and Glycosidic linkage (ii) Essential amino acids and Non-essential amino acids

Following reaction takes place in one step: 2A + B → 2C How will the rate of above reaction change if the volume of the reaction vessel is decreased to one third of its original volume? Will there be any change in the order of reaction with the reduced volume?

For the first order thermal decomposition reaction, following data was obtained: C₂H₅Cl(g) → C₂H₄(g) + HCl(g) | S. No. | Time(s) | Total Pressure (atm) | | 1 | 0 | 0.30 | | 2 | 30 | 0.50 | Calculate rate constant. [Given: $\log 3 = 0.48$]

(a) Answer the following: (3 × 1) (i) Why is the Equilibrium Constant (Kc) related to E°cell and not to Ecell? (ii) Two metals 'A' and 'B' have standard electrode potential values of −0.24 V and +0.80 V respectively. Which of these will liberate hydrogen gas from dil. H₂SO₄? (iii) Write the cell reaction which occurs in lead storage battery when it is in charging. OR (b) What type of battery is Mercury cell? Why it is more advantageous than dry cell? Write overall reaction taking place in Mercury cell.

Calculate the boiling point of a solution containing 0.61 g of benzoic acid ($\text{Molar mass} = 122 \text{ g mol}^{-1}$) in 5 g of CS₂ in which it dimerises to the extent of 88%. The boiling point and Kb of CS₂ are 46.2 °C and $2.3 \text{ K kg mol}^{-1}$ respectively.

Write the reactions of D-Glucose with the following: (3 × 1) (a) HI (b) Br₂ water (c) Conc. HNO₃

Give reasons for the following: (3 × 1) (a) Carboxylic acids have higher boiling point than alcohols of comparable molecular masses. (b) Alpha (α) hydrogens of aldehydes and ketones are acidic in nature. (c) Nucleophilic addition of ammonia and its derivatives does not occur with carbonyl group in strongly acidic medium.

Write the reaction involved in the following: (3 × 1) (a) Reimer-Tiemann reaction (b) Kolbe's reaction (c) Friedel-Crafts acylation of anisole

Compound 'X' with molecular formula C₄H₉Br reacts with aqueous KOH to give an alcohol. The rate of this reaction depends only on the concentration of the compound 'X'. When an optically active isomer 'Y' of the compound 'X' was treated with aqueous KOH solution, the rate of reaction was found to be dependent on concentration of compound 'Y' and aqueous KOH both. (3 × 1) (a) Write down the structural formula of both 'X' and 'Y'. (b) Out of 'X' and 'Y', which one will undergo racemisation and why? (c) Out of 'X' and 'Y', which one will form product with inversion of configuration and why?

(a) (i) Why CH₃ – NH₂ is a stronger base than (CH₃)₃N in aqueous solution? (2 × 1) (ii) Write structural formulae of the compound A and B: CH₃CONH₂ —(NaOBr)→ A —(C₆H₅COCl / Base)→ B

(b) A compound 'X' with molecular formula C₃H₉N reacts with Hinsberg reagent to give a product insoluble in alkali. Identify 'X'. OR (b) How can you convert aniline to benzonitrile?

(c) Why is –NH₂ group of aniline acetylated before carrying out nitration?

(a) In octahedral crystal field, energies of which d-orbitals will be raised when ligands approach the central metal atom/ion? Give reason in support of your answer.

(b) Using crystal field theory, write the electronic configuration of central metal atom/ion of the following: (i) [CoF₆]³⁻ (ii) [Co(NH₃)₆]³⁺ [At. No.: $\text{Co} = 27$]

(c) $[NiCl_4]^{2-}$ is paramagnetic while $[Ni(CO)_4]$ is diamagnetic though both are tetrahedral. Why? [Atomic No.: $Ni = 28$] OR (c) Write hybridization and magnetic behaviour of the complex $[Fe(CN)_6]^{3-}$. [Atomic No.: $Fe = 26$]

(a) (i) An organic compound (X) has the molecular formula $C_5H_{10}O$. Draw structures for (X) if it: (3 + 2) (I) does not give Tollen's test but gives a positive iodoform test. (II) does not give Tollen's test and iodoform test but undergoes Aldol condensation. (III) undergoes Cannizzaro's reaction. (ii) Show how each of the following compounds can be converted to benzoic acid: (I) Acetophenone (II) Ethyl benzene OR (b) Answer the following questions: $(5 \times 1)$ (i) Draw structure of the 2, 4-dinitrophenyl hydrazone derivative of benzaldehyde. (ii) Arrange the following in increasing order of their reactivity towards HCN: Di-tert. butyl ketone, Acetaldehyde, Acetone (iii) Give a simple chemical test to distinguish between benzoic acid and ethyl benzoate. (iv) Write the name of the reagent to convert Ethanenitrile to Ethanal. (v) Draw the structure of 'X' in the following reaction: Cyclohexanol —($CrO_3$)→ 'X'

(a) (i) From the given data of E° values, answer the following questions: (3 + 2) $E^\circ(M^{2+}/M)$ values (V): $V = -1.18, Cr = -0.91, Mn = -1.18, Fe = -0.44, Co = -0.28, Ni = -0.25, Cu = +0.34$ (I) Why $E^\circ(M^{2+}/M)$ show irregular trend in the above values? (II) Why is $E^\circ(Cu^{2+}/Cu)$ value exceptionally positive? (III) Why $E^\circ(Mn^{2+}/Mn)$ value is highly negative? (ii) Write the ionic equations for the oxidising action of potassium permanganate for its reaction with $I^-$ in both acidic and alkaline solutions. OR (b) Answer the following questions: (1 + 1 + 1 + 2) (i) Name a member of the lanthanoid series (I) which exhibits +4 oxidation state (II) which exhibits +2 oxidation state. (ii) Why transition metals act as good catalyst? (iii) Why Cr has higher melting point than Mn? (iv) What happens when acidic solution of potassium permanganate is allowed to stand for sometime? Give the equation involved. What is this type of reaction called?

(a) Calculate emf and $\Delta G$ for the following cell at 298 K: $Mg(s) / Mg^{2+}(0.01\text{ M}) // Ag^+(0.001\text{ M}) / Ag(s)$ Given: $E^\circ(Mg^{2+}/Mg) = -2.37 \text{ V}$, $E^\circ(Ag^+/Ag) = +0.80 \text{ V}$ [$1F = 96500 \text{ C mol}^{-1}$, $\log 10 = 1$] OR (b) For the reaction: $2AgCl(s) + H_2(g) (0.4\text{ atm}) \to 2Ag(s) + 2H^+(0.1\text{ M}) + 2Cl^-(0.2\text{ M})$ Calculate emf of the cell at 25 °C. Given: $\Delta G^\circ = -43500 \text{ J mol}^{-1}$ [$\log 10 = 1$, $1F = 96500 \text{ C mol}^{-1}$]