ISC 2026 Chemistry Question Paper for Class 12

About this paper

This is ISC Class 12 Chemistry Paper 1 (Theory), code 862A, from the 2026 board examination. 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 of fill-in-the-blank items, multiple-choice questions with two assertion–reason items, and a passage on Kohlrausch's law that gives the ionic conductivities of Ba2+, Ca2+, Cl− and SO42−. 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 longer questions include a freezing-point calculation for ascorbic acid in acetic acid, the peptide link between glycine and alanine, and valence-bond questions on [Cr(NH3)6]3+. Constants are printed on the paper. This copy has the questions only.

Exam

ISC Class 12

Subject

Chemistry

Year

2026

Paper code

862A

Maximum marks

70

Time allowed

3 hours + 15 min reading

Questions

21

Pages

11

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 Kohlrausch's law 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

Questions from this paper

1. A reaction is first order in A and second order in B. What is the effect on the rate if only the concentration of B is increased three times, and if the concentrations of both A and B are doubled?
2. 0.680 g of a compound dissolved in 15.0 g of benzene lowers the freezing point by 1.44°C. Calculate the experimental molecular mass. (Kf for benzene = 5.12 K kg mol−1.) If the theoretical molecular mass is 80.5 g mol−1, is the compound associating or dissociating?
3. Write the IUPAC names of [Pt(NH3)4Cl2]SO4 and K2[Ni(CN)4].
4. Calculate ΔG° at 25°C for the cell Zn(s) / Zn2+(1 M) || Sn2+(1 M) / Sn(s). (E°Zn2+/Zn = −0.76 V, E°Sn2+/Sn = −0.14 V, 1 faraday = 96,500 coulombs.)
5. A first-order reaction is 40% complete in 20 minutes. Calculate the time required for 90% completion.
6. Calculate the mass of ascorbic acid (molecular mass 176 g mol−1) to be dissolved in 75 g of acetic acid to lower its freezing point by 1.5°C. (Kf for acetic acid = 3.9 K kg mol−1.)