ISC Chemistry 2026 Improvement Paper with Answers
All 35 questions of the ISC Chemistry 2026 Improvement Paper, in printed order. Open a question to read it in full and see its answer.
- Q1(A)(i) Choose the appropriate word(s) from the bracket [first, zero, second, Raoult’s law, non-ideal, addition, substitution, Henry’s… 1 mark · Fill in
- Q1(A)(ii) Choose the appropriate word(s) from the bracket [first, zero, second, Raoult’s law, non-ideal, addition, substitution, Henry’s… 1 mark · Fill in
- Q1(A)(iii) Choose the appropriate word(s) from the bracket [first, zero, second, Raoult’s law, non-ideal, addition, substitution, Henry’s… 1 mark · Fill in
- Q1(A)(iv) Choose the appropriate word(s) from the bracket [first, zero, second, Raoult’s law, non-ideal, addition, substitution, Henry’s… 1 mark · Fill in
- Q1(B)(i) In the complexes, $[\text{Fe}(\text{CN})_6]^{3-}$ and $[\text{Pt}(\text{en})(\text{H}_2\text{O})_2\text{Br}(\text{NO}_2)]^{2+}$… 1 mark · MCQ
- Q1(B)(ii) Which one of the following properties of transition metals enables them to behave as catalysts? 1 mark · MCQ
- Q1(B)(iii) The reactivity orders of alkyl halides for dehydrohalogenation reaction are given below: (P) $\text{R-I} > \text{R-Br}$ (Q)… 1 mark · MCQ
- Q1(B)(iv) Samantha suffers from deformity of bones. The doctor has advised her to consume a particular vitamin. Identify the vitamin that… 1 mark · MCQ
- Q1(B)(v) Identify the end product [B] in the following sequence of chemical reaction… 1 mark · MCQ
- Q1(B)(vi) Primary, secondary and tertiary alcohols can be distinguished with the help of Lucas reagent. 1 mark · Assertion-reason
- Q1(B)(vii) Osmotic pressure of $0\cdot5\text{ molar}$ $\text{KCl}$ solution is more than that of $0\cdot5\text{ molar}$ urea solution. 1 mark · Assertion-reason
- Q1(C) In the year 1832, Michael Faraday performed many experiments on electrolysis. He established a relationship between the amount of… 3 marks · Case based
- Q2 Consider the mechanism given below derived from spectrochemical analysis of the reaction between $\text{NO}$ and $\text{F}_2$… 2 marks · Short answer
- Q3 During an experiment, a scientist tried to determine the molecular mass of a protein by applying elevation of boiling point… 2 marks · Short answer
- Q4 Calculate the value of $\Delta G^\circ$ for the following cell at $298\text{ K}$… 2 marks · Numerical
- Q5 Carbon dating method is a useful tool to estimate the age of fossils. A radioactive carbon-14 isotope decays with a half-life of… 2 marks · Numerical
- Q6 Account for the following: $\text{Co}^{2+}$ readily loses one electron whereas $\text{Mn}^{3+}$ readily gains one electron… 2 marks · Short answer
- Q7 Using IUPAC nomenclature, write the formula for each of the following: hexaaquairon(II) chloride potassium… 2 marks · Short answer
- Q8 Write the chemical equations to convert each of the following: Chlorobenzene to benzoic acid 1-bromopropane to 2-bromopropane 2 marks · Short answer
- Q9(i) Acetyl chloride is hydrogenated over palladium in presence of barium sulphate in boiling xylene. Write the balanced chemical… 2 marks · Short answer
- Q9(ii) Write chemical equations to convert each of the following: Toluene to benzaldehyde Acetic acid to acetamide 2 marks · Short answer
- Q10 Write chemical tests to distinguish between the following pairs of compounds: Phenol and acetic acid Ethanol and methanol 2 marks · Short answer
- Q11 Write a chemical equation for each of the following named organic reactions: Carbylamine reaction Mendius reaction 2 marks · Short answer
- Q12 Complete and balance the following reactions: (a)… 3 marks · Short answer
- Q13 Mention two examples of fat-soluble vitamins. Name two pyrimidine bases present in RNA. What is a zwitter ion? Draw a structure… 3 marks · Short answer
- Q14 Write the structural formula of the main organic compound formed in each of the following reactions… 3 marks · Short answer
- Q15 Write chemical equations to convert each of the following: Propan-1-ol to propyl cyanide Sodium methoxide to dimethyl ether… 3 marks · Short answer
- Q16 Identify the compounds [A], [B] and [C] in the following reactions… 3 marks · Short answer
- Q17 How will the rate of reaction be affected by the presence of catalyst? The rate constant for a reaction is… 3 marks · Numerical
- Q18(i) (1) Calculate the charge required in coulombs to deposit $6\cdot35\text{ g}$ of copper at cathode from $\text{CuSO}_4$ solution… 3 marks · Short answer
- Q18(ii) Ionic conductance at infinite dilution of $\text{Al}^{3+}$ and $\text{SO}_4^{2-}$ ions are… 3 marks · Numerical
- Q19 What happens when (write chemical equations): (a) Benzaldehyde is heated with alcoholic $\text{KCN}$. (b) Formaldehyde is heated… 5 marks · Short answer
- Q20 An aqueous solution containing $1\cdot25\text{ g}$ $\text{BaCl}_2$ (molecular mass $208\cdot34\text{ g mol}^{-1}$) in… 5 marks · Short answer
- Q21(i) On the basis of Valence Bond Theory (VBT), state the following regarding $[\text{CoF}_6]^{3-}$ complex ion: (Atomic Number of… 5 marks · Short answer
- Q21(ii) $[\text{NiCl}_4]^{2-}$ is paramagnetic while $[\text{Ni}(\text{CO})_4]$ is diamagnetic though both are tetrahedral. Explain the… 5 marks · Short answer