CBSE Class 12 Chemistry 2026 — Set 56/2/1

Which of the following molecules is chiral in nature ? (A) Propan-2-ol (B) Butan-2-ol (C) 1-Bromobutane (D) 2-Bromopropane

Identify the correct increasing order of boiling points of the given compounds : (A) Propan-1-ol < butan-1-ol < butan-2-ol < pentan-1-ol (B) Pentan-1-ol < butan-1-ol < butan-2-ol < Propan-1-ol (C) Propan-1-ol < butan-2-ol < butan-1-ol < pentan-1-ol (D) Butan-1-ol < Butan-2-ol < Propan-1-ol < Pentan-1-ol

Identify the compound produced by the reduction of Ethanenitrile with Lithium aluminium hydride : (A) Ethylamine (B) Ethanal (C) Propylamine (D) Methylamine

The base which is present in DNA but not in RNA is : (A) Guanine (B) Cytosine (C) Thymine (D) Adenine

Proteins are polymers of α-amino acids which are joined to each other by : (A) Covalent Bond (B) Peptide Bond (C) Glycosidic Bond (D) Coordinate Bond

Which of the following reactions is not explained by the open chain structure of glucose ? (A) Glucose on prolonged heating with HI forms n-hexane. (B) Glucose reacts with hydroxylamine to form an oxime. (C) Glucose gets oxidized to gluconic acid on reaction with bromine water. (D) Glucose exists in two different crystalline forms, alpha (α) and beta (β).

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 : (A) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A). (B) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A). (C) Assertion (A) is true, but Reason (R) is false. (D) Assertion (A) is false, but Reason (R) is true. Assertion (A) : The molecularity of the given reaction is 2 2HI arrow H₂ + I₂ Reason (R) : Two molecules of the reactants are involved in simultaneous collision between them.

Assertion (A) : Zinc, cadmium and mercury are not considered as transition elements. Reason (R) : These elements have completely filled orbitals in their ground state as well as in their common oxidation states.

Assertion (A) : Aromatic primary amines can be prepared by Gabriel Phthalimide synthesis. Reason (R) : Aryl halides do not undergo nucleophilic substitution with the anion formed by phthalimide.

Assertion (A) : Glucose gets oxidized to six carbon gluconic acid on reaction with bromine water. Reason (R) : The carbonyl group is absent in the open chain structure of glucose.

(A) The concentration of the reactant is reduced from 0.6 mol L⁻¹ to 0.2 mol L⁻¹ in 5 minutes in a first order reaction. Calculate rate constant of the reaction. (log 3 = 0.48) OR (B) Rate constant k for the first order reaction is 2.54 × 10⁻³ s⁻¹. Calculate the time required for three-fourth of the reactant to decompose. (log 4 = 0.60)

(a) Define activation energy. (b) Write the unit of rate constant for (i) zero order reaction, (ii) second order reaction.

(a) First ionization enthalpy of Cr is lower than that of Zn. Why ? (b) Mention any one property of the transition elements which makes them good catalysts.

(a) Define coordination number. (b) Indicate the type of isomerism exhibited by the following complex : [Co(en)₃]Cl₃

(a) Draw the structure of the given compound : 4-Bromo-3-methylpent-2-ene (b) What happens when chloroethane is treated with aqueous potassium hydroxide ?

When 1.5 g of a non-volatile solute was dissolved in 90 g of benzene, the boiling point of benzene got raised from 353.23 K to 353.93 K. Calculate the molar mass of the solute. (Given Kb for benzene = 2.52 K kg mol⁻¹)

Calculate emf of the following cell at 298 K : Sn|Sn²⁺(0.001M)||H^+(0.01M)|H₂(g)(1bar)|Pt(s) Given : EoSn²⁺/Sn = -0.14 V, EoH^+/H_2 = 0.00 V [log 10 = 1]

(a) Complete and balance the following equations : (i) 2KMnO₄ xrightarrow513K (ii) Na₂Cr₂O₇ + 2KCl arrow (b) Why is it difficult to separate lanthanoid elements in pure state ?

(a) [Co(NH₃)₆]³⁺ is diamagnetic whereas [CoF₆]³⁻ is paramagnetic. Justify the statement. [Atomic number of Co = 27] (b) Write the electronic configuration for d⁴ ion if Δ₀ > P on the basis of crystal field theory.

(a) Write the major product in the following reactions : Cyclohexene (C₆H₁₀, drawn as a six-membered ring with one C=C) + Br₂ xrightarrowheat ? (b) Define Racemic mixture. (c) p-dichlorobenzene has a higher melting point as compared to its ortho and meta isomers. Why ?

Write the reaction involved in (a) Rosenmund's reduction (b) Cannizzaro's reaction (c) Hell-Volhard-Zelinsky reaction

(A) Define the following term : (a) Reducing sugar (b) Differentiate between the following : (i) Fibrous proteins and globular proteins (ii) Nucleotide and nucleoside OR (B) Write the reaction of glucose with the following : (a) H₂N-OH (b) (CH₃CO)₂O (c) conc. HNO₃

The following questions are case-based questions. Each question has an internal choice and carries 4 (2+1+1) marks each. Read the passage carefully and answer the questions that follow : Osmosis is a process by which the molecules of a solvent pass from a solution of low solute concentration to a solution of high solute concentration through a semi-permeable membrane. Osmotic pressure is a colligative property. When the applied pressure on a solution exceeds its osmotic pressure, reverse osmosis occurs. When two solutions are separated by a semipermeable membrane and they have same osmotic pressure they are said to be isotonic. Of the two solutions separated by a semipermeable membrane, if one is a lower osmotic pressure, it is said to be hypotonic relative to the second solution. If it has a higher osmotic pressure, than the second solution, it is said to be hypertonic relative to the second solution. The osmotic pressure associated with the fluid inside the blood cell is equivalent to that of 0.9% (mass/volume) sodium chloride solution called normal saline solution and it is safe to inject intravenously. Osmotic pressure is vital in daily life and nature. It helps in explain, why IV fluids match blood's osmotic pressure, its also the principle behind food preservation using salt or sugar. (a) Calculate the amount of CaCl₂ (i = 2.59) dissolved in 2.46 litre of water such that its osmotic pressure is 0.70 atm at 27°C. [Given : R = 0.082 L atm K⁻¹ mol⁻¹, molar mass of CaCl₂ = 111 g mol⁻¹] (b) When raisins are kept in water, they get swollen. Name the phenomenon involved in this process. OR (b) Why osmotic pressure is more advantageous than other colligative properties ? (c) Which phenomenon is responsible for desalination of sea water ?

Like NH₃, nitrogen atom of amine is trivalent and carries an unshared pair of electrons. Nitrogen orbitals in amines are therefore sp³ hybridised and the geometry of amines is pyramidal. Lower aliphatic amines are soluble in water due to the formation of hydrogen bond with water molecules. The solubility decreases as the molar mass of amines increases due to increase in size of hydrophobic part. Higher amines are insoluble in water. However amines are less soluble in water than alcohols because of low electronegativity of nitrogen as compared to oxygen. Boiling points of isomeric amines follow the order 1º > 2º > 3º. It is due to the fact the amines are held together due to hydrogen bonding. Extent of hydrogen bonding is more in primary amines than in secondary amines as two hydrogen atoms are available for hydrogen bond formation. Tertiary amines do not show hydrogen bonding because of the absence of hydrogen atom attached to nitrogen. Amines can be prepared from, nitro compounds, nitriles, amides etc. (a) Complete the following equations : (i) CH₃CONH₂ xrightarrow[(ii) H₂O](i) LiAlH₄ (ii) 4-Nitrotoluene (4-CH₃C₆H₄NO₂, drawn: benzene ring with NO₂ and CH₃ para to each other) xrightarrowFe + HCl (b) Why primary amines have higher boiling points than tertiary amines ? (c) Classify the following amines as primary, secondary or tertiary : (i) N,N-dimethylnaphthalen-2-amine (drawn: naphthalene bearing -N(CH₃)₂) (ii) Naphthalen-2-amine (drawn: naphthalene bearing -NH₂) OR (c) Out of Butan-1-amine and Butan-1-ol, which is more soluble in water ?

(A) (a) How will you convert the following : (i) Propanone to Propene (ii) Benzoic acid to Benzaldehyde (iii) Benzene to m-Nitroacetophenone (b) (i) Arrange the following compounds in increasing order of their reactivity towards HCN : Propanone (CH₃)₂C=O, Di-tert-butyl ketone ((CH₃)₃C)₂C=O, Ethanal CH₃CHO (ii) Identify the compounds, which would undergo Aldol condensation : Methanal, HCHO Benzaldehyde, C₆H₅CHO Ethanal, CH₃CHO Cyclohexanone (C₆H₁₀O, drawn) OR (B) (a) Give chemical tests to distinguish between the following pairs of compounds : (i) Acetophenone and Benzophenone (ii) Propanal and Propanone (iii) Pentan-2-one and Pentan-3-one (b) (i) Which of the following acids is stronger and why ? CH₂FCOOH, CH₃COOH (ii) Arrange the following compounds in the increasing order of their boiling points : CH₃OCH₃, CH₃CH₂CH₃, CH₃CH₂OH, CH₃CHO

(A) (a) The conductivity of 0.1 mol L⁻¹ solution of NaCl is 1.06 × 10⁻² S cm⁻¹. Calculate its molar conductivity and degree of dissociation. λoNa^+ = 50.1 S cm² mol⁻¹, λoCl^- = 76.5 S cm² mol⁻¹ (b) (i) Following cell reaction occurs in a galvanic cell : 2Ag^+(aq) + Zn(s) arrow 2Ag(s) + Zn²⁺(aq), Eo(cell) = +1.56 V Predict the direction of flow of current. (ii) Differentiate between a primary battery and a secondary battery. OR (B) (a) Resistance of a conductivity cell filled with 0.1 M KCl solution is 100 Ω. If the resistance of the same cell when filled with 0.01 mol L⁻¹ KCl solution is 300 Ω, calculate the conductivity and molar conductivity of 0.01 mol L⁻¹ KCl solution. The conductivity of 0.1 M KCl solution is 1.29 × 10⁻² S cm⁻¹. (b) (i) Write any two advantages of H₂ - O₂ fuel cell. (ii) Why does the cell potential of mercury cell remain constant throughout the life ?

(A) An organic compound 'A', with molecular formula C₂H₆O reacts with active metals such as sodium to give compound 'B' and hydrogen gas. 'A' on treatment with iodine and sodium hydroxide gives 'C' and in presence of H₂SO₄ at 413 K gives 'D' (C₄H₁₀O). 'D' on reaction with excess of HI gives 'E'. Identify 'A', 'B', 'C', 'D' and 'E' and write all the reactions involved. OR (B) (a) Write the reagents which are used in the given conversions : (i) Phenol to 2, 4, 6-tribromophenol (ii) Propene to propan-1-ol (iii) Butan-2-one to butan-2-ol (b) Explain the mechanism of acid catalyzed hydration of alkene to form corresponding alcohol.