CBSE Class 12 PCM Chemistry Board Paper 2026 — Set 2

Identify the correct statement :

Electronic configuration of chromium is :

The correct IUPAC name of the complex [Pt(NH₃)₂Cl₂] is :

Which of the following is heteroleptic complex ?

Which of the following molecules is chiral in nature ?

Identify the correct increasing order of boiling points of the given compounds :

The base which is present in DNA but not in RNA is

Proteins are polymers of α-amino acids which are joined to each other by :

Which of the following reactions is not explained by the open chain structure of glucose ?

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.

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)

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 K_b for benzene = 2.52 K kg mol⁻¹)

Calculate emf of the following cell at 298 K :

Sn | Sn²⁺ (0.001 M) || H⁺ (0.01 M) | H₂(g) (1 bar) | Pt(s)

Given : E°_Sn²⁺/Sn = – 0.14 V,

E°_H⁺/H₂ = 0.00 V [log 10 = 1]

Complete and balance the following equations :

(i) 2KMnO₄ −513 K→

(ii) Na₂Cr₂O₇ + 2KCl →

(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.

(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

Define the following term:

(a) Reducing sugar

(b) Differentiate between the following :

(i) Fibrous proteins and globular proteins

(ii) Nucleotide and nucleoside

Write the reaction of glucose with the following :

(a) H₂N – OH

(b) (CH₃CO)₂O

(c) conc.HNO₃

(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) 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.

λ°_Na⁺ = 50.1 S cm² mol⁻¹

λ°_Cl⁻ = 76.5 S cm² mol⁻¹

(b) (i) Following cell reaction occurs in a galvanic cell :

2Ag⁺(aq) + Zn(s) → 2Ag(s) + Zn²⁺ (aq) E°_(cell) = +1.56 V

Predict the direction of flow of current.

(ii) Differentiate between a primary battery and a secondary battery.

(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 ?

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.

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.

(a) How will you convert the following :

(i) Propanone to Propene

(ii) Benzoic acid to Benzaldehyde

(iii) Benzene to m-Nitroacetophenone