ISC 2026 Chemistry Improvement Examination Question Paper for Class 12

About this paper

This is the ISC Class 12 Chemistry Paper 1 (Theory) from the 2026 improvement examination, code 862A-I.E. It carries 70 marks over three hours, with fifteen minutes to read the paper, and has 21 compulsory questions. Section A is a 14-mark question whose passage is on Faraday's laws of electrolysis, including the charge needed to deposit 27 g of aluminium. Section B has ten two-mark questions, Section C seven three-mark questions and Section D three five-mark questions, with one internal choice in each of those sections. The paper also asks for the age of a wooden artifact from carbon-14 data, the molecular mass of a protein from its osmotic pressure, and the hybridisation and magnetic behaviour of [CoF6]3−. Constants are printed for the calculations. This copy has the questions only.

Exam

ISC Class 12

Subject

Chemistry

Year

2026

Paper code

862A-I.E.

Maximum marks

70

Time allowed

3 hours + 15 min reading

Questions

21

Pages

12

Answers included

No, questions only

Paper pattern

• Section A

  14 marks

  Question 1 with 14 one-mark sub-parts: four fill-in-the-blanks, seven multiple-choice items (two assertion–reason) and three questions on a Faraday's laws passage

• Section B

  20 marks

  Questions 2–11, two marks each; internal choice in one question

• Section C

  21 marks

  Questions 12–18, three marks each; internal choice in one question

• Section D

  15 marks

  Questions 19–21, five marks each; internal choice in one question

Topics covered

• Chemical kinetics
• Solutions and colligative properties
• Electrochemistry
• Coordination compounds
• d-block elements
• Haloalkanes and haloarenes
• Alcohols and phenols
• Aldehydes and ketones
• Amines
• Biomolecules
• Radioactive decay

Questions from this paper

1. For the reaction 2NO + F2 → 2NOF, the slow step is NO + F2 → NOF2. Write the rate law, state the overall order, and find how many times the rate increases if [NO] is doubled and [F2] is tripled.
2. 20 g of a protein in 2 litres of solution has an osmotic pressure of 0.0171 atm at 25°C. Calculate the molecular mass of the protein. (R = 0.0821 dm³ atm K−1 mol−1.)
3. Carbon-14 decays with a half-life of 5730 years. An ancient wooden artifact has only 80% of the C-14 content of a living plant. Calculate the age of the artifact.
4. Calculate ΔG° at 298 K for 2Cr(s) + 3Cd2+(1 M) → 2Cr3+(1 M) + 3Cd(s). (E°Cr3+/Cr = −0.74 V, E°Cd2+/Cd = −0.40 V, 1 faraday = 96,500 coulombs.)
5. Using IUPAC nomenclature, write the formulae of hexaaquairon(II) chloride and potassium tetrachloridoplatinate(II).
6. An aqueous solution containing 1.25 g of BaCl2 (molecular mass 208.34 g mol−1) in 100 g of water boils at 100.085°C. Calculate the degree of dissociation of BaCl2. (Kb for water = 0.52 K kg mol−1.)