ISC Chemistry 2025 Improvement Paper with Answers
All 35 questions of the ISC Chemistry 2025 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 [ethanol, [Fe(H2O)6]2+, anode, d2sp3, Cannizzaro, reducing, cathode, sp3d2… 1 mark · Fill in
- Q1(A)(ii) Choose the appropriate word(s) from the bracket [ethanol, [Fe(H2O)6]2+, anode, d2sp3, Cannizzaro, reducing, cathode, sp3d2… 1 mark · Fill in
- Q1(A)(iii) Choose the appropriate word(s) from the bracket [ethanol, [Fe(H2O)6]2+, anode, d2sp3, Cannizzaro, reducing, cathode, sp3d2… 1 mark · Fill in
- Q1(A)(iv) Choose the appropriate word(s) from the bracket [ethanol, [Fe(H2O)6]2+, anode, d2sp3, Cannizzaro, reducing, cathode, sp3d2… 1 mark · Fill in
- Q1(B)(i) Ethylamine reacts with nitrous acid at low temperature to form: 1 mark · MCQ
- Q1(B)(ii) Which one of the following statements are correct regarding the depression of freezing point? (P) The depression in freezing… 1 mark · MCQ
- Q1(B)(iii) The amount of bromine required to completely convert $9\cdot4\text{ g}$ of phenol into 2,4,6 tribromophenol is: (Atomic weight of… 1 mark · MCQ
- Q1(B)(iv) Which one of the following statements is correct? 1 mark · MCQ
- Q1(B)(v) What type of structural isomerism exists between the following pair of coordination compounds?… 1 mark · MCQ
- Q1(B)(vi) The use of phosphorus chlorides is preferred to thionyl chloride in the preparation of alkyl chlorides from alcohol. Given below… 1 mark · Assertion-reason
- Q1(B)(vii) The basic strength of hydroxides of lanthanoids decreases with an increase in their atomic number. Given below are two statements… 1 mark · Assertion-reason
- Q1(C) In the year 1889, Svante Arrhenius proposed that the dependence of the rate constant ($k$) of a reaction on temperature can be… 3 marks · Case based
- Q2 Sudeshna took her gold plated bangles to a goldsmith for cleaning and electroplating as they had become black due to constant… 2 marks · Numerical
- Q3 An organic compound [A] having molecular formula $\text{C}_3\text{H}_6\text{O}$ gives a positive iodoform test. On reduction by… 2 marks · Short answer
- Q4 Write chemical equations to convert the following: Chlorobenzene to biphenyl Chloroform to acetylene 2 marks · Short answer
- Q5 The half-life period for radioactive carbon, $^{14}\text{C}$ is $5730\text{ years}$. An ancient sample of wood has only $80\%$ of… 2 marks · Numerical
- Q6 An aromatic compound [A] on heating with aqueous ammonia forms compound [B]. Upon heating with $\text{Br}_2$ and $\text{KOH}$… 2 marks · Short answer
- Q7 Neha and Imran were given an assignment on the coordination complex $[\text{Co}(\text{NH}_3)_6]\text{Cl}_3$. They had to find the… 2 marks · Short answer
- Q8(i) Identify the compounds [A] and [B] in the following reactions… 2 marks · Short answer
- Q8(ii) An aromatic organic compound [A] with the molecular formula $\text{C}_7\text{H}_6\text{O}$ reduces Tollen’s reagent and undergoes… 2 marks · Short answer
- Q9 An organic compound [A] reacts with $\text{PBr}_3$ and forms compound [B] which reacts with magnesium in presence of ether and… 2 marks · Short answer
- Q10 The specific conductivity of $0\cdot0025\text{ M}$ acetic acid solution is… 2 marks · Numerical
- Q11 Write chemical tests to distinguish between the following pairs of compounds: 2-methylpropan-2-ol and propan-2-ol Ethanol and… 2 marks · Short answer
- Q12 Identify [A], [B] and [C] in the following reactions: Identify [A] and [B] in reaction (i). Identify [C] in reaction (ii). 3 marks · Short answer
- Q13 The colligative properties are properties of solutions which depend only upon the number of solute particles irrespective of… 3 marks · Short answer
- Q14 Write chemical equations to illustrate the following name reactions: Clemmensen’s reduction Cross Aldol condensation Kolbe’s… 3 marks · Short answer
- Q15 Answer the following: $[\text{Co}(\text{NH}_3)_6]^{3+}$ is an inner orbital complex whereas $[\text{CoF}_6]^{3-}$ is an outer… 3 marks · Short answer
- Q16(i) Answer the following questions: State Kohlrausch’s law of independent migration of ions. Calculate the molar conductivity of an… 3 marks · Short answer
- Q16(ii) Answer the following questions: What should be the sign (positive or negative) for $E^\circ_{\text{cell}}$ and $\Delta G^\circ$… 3 marks · Short answer
- Q17 Answer the following: What is observed when D-glucose is treated with bromine water? Write the chemical reaction. Though vitamin… 3 marks · Short answer
- Q18 Following rate data was obtained at 298 K for the reaction $\text{A} + \text{B} \longrightarrow \text{C} + \text{D}$: Answer the… 3 marks · Numerical
- Q19 Alcohols are the compounds that have one or more hydroxyl groups bonded to aliphatic carbon atoms while phenols are the compounds… 5 marks · Short answer
- Q20 Answer the following: Give a reason: Transition elements show high melting point. Give a reason: Though $\text{Zr}$ ($Z = 40$)… 5 marks · Short answer
- Q21(i) The pressure exerted by the vapour of a liquid at a particular temperature is known as the vapour pressure of the liquid at that… 5 marks · Short answer
- Q21(ii) Answer the following questions: A solution of an organic compound is prepared by dissolving $34\cdot2\text{ g}$ of solute in… 5 marks · Short answer