Class 12 ISC Chemistry Answer Key 2025 (Available): Unofficial keys PDF download
For the exam held on February 24, Class 12 ISC Chemistry Answer Key 2025 has been provided here. The answer key is unofficial and given for all set codes.
Class 12 ISC Chemistry Answer Key 2025: Candidates can check out the Class 12 ISC Chemistry Answer Key 2025, which has been updated here. Through this, candidates can know the unofficial answers to the objective questions that our subject experts have provided. As a result, candidates can see the answers for all questions asked in Section A Question 1, Part A, Part B, and Part C. Since all other questions until Question 21, and Sections B, C, Section D are subjective questions, the answers to the same will not be stated. Candidates can evaluate their performance by checking the answer key and determining their test scores. The answer keys has been provided for all sets.
Also Read | Class 12 ISC Result Expected Release Date 2025
Class 12 ISC Chemistry Answer Key 2025
Aspirants can check the unofficial answer key for the ISC Class 12 Chemistry 2025 exam in the table below.
Section A Question 1 (Part - A)
| Question Number | Answer Key |
| (i) _____ is an example of a primary cell but _____ is an example of a secondary cell. | Dry Cell, Nickel-cadmium cell |
| (ii) The complex compound [Ni(CO)4] is ______ in shape and nickel is in ____ oxidation state in this complex compound. | Tetrahedral, Zero |
| (iii) When acetaldehyde is treated with hydrazine and KOH in a high boiling solvent glycol, _____ is formed and the reaction is known as _____ reduction. | Ethane, Wolff-Kishner |
| (iv) The transition metal ions having _____ d-orbitals are colourless and _____ in nature. | Completely filled, Diamagnetic |
Section A Question 1 (Part - B)
| Question Number | Answer Key |
| (i) Which one of the following can produce the foul smelling compound methyl isocyanide in presence of alcoholic KOH? (a) Chloroform and aniline (b) Chloroform and methanol (c) Chloroform and dimethyl amine (d) Chloroform and methyl amine | (d) Chloroform and methyl amine |
| (ii) The osmotic pressure of a solution: (P) Increases with an increase in number of moles of solute (Q) Decreases with an increase in number of moles of solute (R) Increases at a higher temperature (S) Is dependent on the nature of solute Which one of the following is correct? (a) Only P and Q are correct (b) Only P and R are correct (c) Only P and S are correct (d) Only Q and S are correct | (b) Only P and R are correct |
| (iii) Which one of the following alcohols is the strongest acids? (a) Phenol (b) Methanol (c) Ethanol (d) t-butyl alcohol | (a) Phenol |
| (iv) Which one of the following does NOT form a silver mirror on heating with Tollen's reagent? (a) Glucose (b) Fructose (c) Sucrose (d) Lactose | (c) Sucrose |
| (v) The coordination number and the oxidation state of the central metal 'D' in the complex [D(en)2(H2O)2]Cl3 are: (a) 6 and 2 respectively (b) 4 and 2 respectively (c) 3 and 6 respectively (d) 6 and 3 respectively | (d) 6 and 3 respectively |
| (vi) Given below are two statements marked Assertion and Reason. Read the two statements carefully and select the correct option. Assertion: The process of halogenation of benzene takes place in the presence of anhydrous FeCl3 Reason: Anhydrous FeCl3 prepares nucleophiles to attack the benzene ring. (a) Both Assertion and Reason are true and Reason is the correct explanation for Assertion. (b) Both Assertion and Reason are true but Reason is not the correct explanation for Assertion. (c) Assertion is true and Reason is false. (d) Both Assertion and Reason are false. | (c) Assertion is true and Reason is false. |
| (vii) Given below are two statements marked Assertion and Reason. Read the two statements carefully and select the correct option. Assertion: The Zr-Hf pair of elements has the same value of atomic radii though Zr and Hf are placed in different periods in the periodic table. Reason: The lanthanoid contraction prevents the expected increase in atomic radii of Hf. (a) Both Assertion and Reason are true and Reason is the correct explanation for Assertion. (b) Both Assertion and Reason are true but Reason is not the correct explanation for Assertion. (c) Assertion is true and Reason is false. (d) Both Assertion and Reason are false. | (a) Both Assertion and Reason are true and Reason is the correct explanation for Assertion. |
Section A Question 1 (Part - C)
Question Number | Answer Key |
| (i) What will be the order of reaction if the unit of k is mol-2L2s-1? | Third Order |
| (ii) State any one difference between the order of reaction and molecularity of a reaction. | The order of a reaction is determined experimentally based on the rate law and can be a fraction or zero, while molecularity refers to the number of reactant molecules involved in an elementary reaction step and is always a whole number. |
| (iii) For the reaction 2A ----> B + C, the rate law is rate = k[A]3/2. What is the order and molecularity of the reaction? | Mol = 2 |
Class 12 ISC Chemistry Exam Analysis 2025 Link
Candidates can check out the ISC Class 12 Chemistry Exam Analysis 2025 by clicking here:
Class 12 ISC Subject-Wise Answer Key 2025 |
| Name of Subject | Answer Key 2025 Links |
| English Language | Class 12 ISC English Language Answer Key 2025 |
| English Literature | Class 12 ISC English Literature Answer Key 2025 |
| Economics | Class 12 ISC Economics Answer Key 2025 |
| Mathematics | Class 12 ISC Mathematics Answer Key 2025 |
| Business Studies | Class 12 ISC Business Studies Answer Key 2025 |
| Physics | Class 12 ISC Physics Answer Key 2025 |
| Commerce | Class 12 ISC Commerce Answer Key 2025 |
| Accounts | Class 12 ISC Accounts Answer Key 2025 |
| Biology | Class 12 ISC Biology Answer Key 2025 |
| Computer Science | Class 12 ISC Computer Science Answer Key 2025 |
| Physical Education | Class 12 ISC Physical Education Answer Key 2025 |
For live updates on the answer key, exam analysis, and student reviews, candidates must stay tuned on this page for real-time updates.
Class 12 ISC Chemistry Answer Key 2025 Live Updates
Feb 24, 2025 11:00 PM IST
ISC Class 12 Chemistry Answer Key 2025: Section A Question 1 (Cii) Answer
Ques: State one difference between the order of reaction and molecularity of reaction.
Ans: The order of a reaction is determined experimentally based on the rate law and can be a fraction or zero, while molecularity refers to the number of reactant molecules involved in an elementary reaction step and is always a whole number.
Feb 24, 2025 10:40 PM IST
ISC Class 12 Chemistry Answer Key 2025: Section A Question 1 (Ci) Answer
Ques: (i) What will be the order of reaction if the unit of k is mol-2L2s-1?
Ans: Third Order
Feb 24, 2025 10:20 PM IST
Class 12 ISC Chemistry Answer Key 2025: Section A Question 1 (Biii) Answer
Ques: (iii) Which one of the following alcohols is the strongest acids?
(a) Phenol
(b) Methanol
(c) Ethanol
(d) t-butyl alcoholAns: Option A
Feb 24, 2025 10:00 PM IST
Class 12 ISC Chemistry Answer Key 2025: Section A Question 1 (Bii) Answer
Ques: (ii) The osmotic pressure of a solution:
(P) Increases with an increase in number of moles of solute
(Q) Decreases with an increase in number of moles of solute
(R) Increases at a higher temperature
(S) Is dependent on the nature of solute
Which one of the following is correct?
(a) Only P and Q are correct
(b) Only P and R are correct
(c) Only P and S are correct
(d) Only Q and S are correctAns: Option B
Feb 24, 2025 09:40 PM IST
Class 12 ISC Chemistry Answer Key 2025: Section A Question 1 (Bi) Answer
Ques: (i) Which one of the following can produce the foul smelling compound methyl isocyanide in presence of alcoholic KOH?
(a) Chloroform and aniline
(b) Chloroform and methanol
(c) Chloroform and dimethyl amine
(d) Chloroform and methyl amineAns: Option D
Feb 24, 2025 09:20 PM IST
ISC Class 12 Chemistry Answer Key 2025: Section A Question 1 (Aiv) Answer
Ques: (iv) The transition metal ions having _____ d-orbitals are colourless and _____ in nature.
Ans: Completely filled, Diamagnetic
Feb 24, 2025 09:00 PM IST
ISC Class 12 Chemistry Answer Key 2025: Section A Question 1 (Aiii) Answer
Ques: (iii) When acetaldehyde is treated with hydrazine and KOH in a high boiling solvent glycol, _____ is formed and the reaction is known as _____ reduction.
Ans: Ethane, Wolff-Kishner
Feb 24, 2025 08:40 PM IST
ISC Class 12 Chemistry Answer Key 2025: Section A Question 1 (Aii) Answer
Ques: (ii) The complex compound [Ni(CO)4] is ______ in shape and nickel is in ____ oxidation state in this complex compound.
Ans: Tetrahedral, Zero
Feb 24, 2025 08:20 PM IST
ISC Class 12 Chemistry Answer Key 2025: Section A Question 1 (Ai) Answer
Ques: (i) _____ is an example of a primary cell but _____ is an example of a secondary cell.
Ans: Dry cell, Nickel-cadmium cell
Feb 24, 2025 08:00 PM IST
ISC Class 12 Chemistry Answer Key 2025: Student Reactions
Some students opined that the paper was moderate. There were no out-of-the syllabus questions, however, the easy and the letter writing topics could have been easy. Grammar and Comprehension section were the easiest.
Feb 24, 2025 07:40 PM IST
ISC Class 12 Chemistry Answer Key 2025: Was the paper time-consuming?
As per the student reviews, the paper was not time-consuming.
Feb 24, 2025 07:20 PM IST
Class 12 ISC Chemistry Answer Key 2025: Which was the lengthiest section?
As per the student reviews, the lengthiest section was Section D in the question paper, compared to other sections.
Feb 24, 2025 07:00 PM IST
Class 12 ISC Chemistry Answer Key 2025: Expected Good Score
As per the candidates, the expected good score can be 60+.
Feb 24, 2025 06:45 PM IST
Class 12 ISC Chemistry Answer Key 2025: Difficulty Level of Section D
Based on the initial feedback, the overall difficulty level of Section D is moderate.
Feb 24, 2025 06:30 PM IST
Class 12 ISC Chemistry Answer Key 2025: Difficulty Level of Section C
Based on the initial feedback, the overall difficulty level of Section C is moderate.
Feb 24, 2025 06:15 PM IST
Class 12 ISC Chemistry Answer Key 2025: Difficulty Level of Section B
Based on the initial feedback, the overall difficulty level of Section B is easy to moderate.
Feb 24, 2025 06:00 PM IST
Class 12 ISC Chemistry Answer Key 2025: Difficulty Level of Section A
Based on the initial feedback, the overall difficulty level of Section A is easy.
Feb 24, 2025 05:45 PM IST
Class 12 ISC Chemistry Answer Key 2025: Overall Difficulty Level of the Paper
Based on the initial feedback, the overall difficulty level of the paper is moderate.
Feb 24, 2025 05:30 PM IST
12th ISC Chemistry Answer Key 2025 Was 2024 paper time-consuming?
No, 12th ISC Chemistry 2024 examination was not really time-consuming.
Feb 24, 2025 05:15 PM IST
ISC 12th Chemistry Answer Key 2025: Overall Difficulty of 2024 Paper
The overall difficulty level of ISC 12th Chemistry 2024 examination was moderate.
Feb 24, 2025 05:00 PM IST
Class 12 ISC Chemistry Answer Key 2025: Exam Has Concluded
The examination is finally over. Stay tuned on the page for the unofficial answer key, which will be provided by our subject experts.
Feb 24, 2025 04:40 PM IST
Class 12 ISC Chemistry Answer Key 2025: Previous Year Question 3
Assertion (A): Ammonolysis of alkyl halides involves the reaction between alkyl halides and alcoholic ammonia.
Reason (R): Ammonolysis of alkyl halides produces secondary amines only.
(a) Both Assertion and Reason are true and Reason is the correct explanation for Assertion.
(b) Both Assertion and Reason are true but Reason is not the correct explanation for Assertion. (c) Assertion is true but Reason is false. (d) Assertion is false but Reason is true.
Feb 24, 2025 04:20 PM IST
12th ISC Chemistry Answer Key 2025: Previous Year Question 2
An equimolar solution of non-volatile solutes A and B, shows a depression in freezing point in the ratio of 2:1. If A remains in its normal state in the solution, the state of B in the solution will be:
(a) normal.
(b) hydrolysed.
(c) associated.
(d) dissociated.
Feb 24, 2025 04:00 PM IST
Class 12 ISC Chemistry Answer Key 2025: Remaining One Hour
Candidates must start revising their papers as only 1 hour is left for the test to conclude.
Feb 24, 2025 03:40 PM IST
ISC 12th Chemistry Answer Key 2025: Previous Year Question 1
The addition of small quantity of ethanol to chloroform prevents the formation of _______ and converts it into the harmless compound _______.
Feb 24, 2025 03:20 PM IST
ISC Class 12 Chemistry Answer Key 2025: Will the answer key provided for subjective questions?
Our subject experts will provide ISC Class 12 Chemistry Answer Key 2025 only for the objective questions of the paper.
Feb 24, 2025 03:00 PM IST
Class 12 ISC Chemistry Answer Key 2025: Nature of the Answer Key
The answer provided on the page below will be unofficial and provisional in nature. Candidates must only take the answers as reference to understand how their performance went.
Feb 24, 2025 02:40 PM IST
12th ISC Chemistry Answer Key 2025 What is the marking scheme?
For correct answers in Sections A, B, C, and D, candidates will get 1 mark, 2 marks, 3 marks, and 5 marks, respectively. There is no negative marking on the paper.
Feb 24, 2025 02:20 PM IST
ISC 12th Chemistry Answer Key 2025: What is the question pattern?
The ISC 12th Chemistry 2025 question paper comprises questions from three units. Unit 1 is of 25 marks, Unit 2 is of 20 marks, and Unit 3 is of 25 marks. The total mark of the paper is 70.
Feb 24, 2025 02:00 PM IST
Class 12 ISC Chemistry Answer Key 2025: Exam Has Begun
Class 12 ISC Chemistry 2025 examination has begun. The doors are shut, the bells have rung, and the students are now answering the paper.
Feb 24, 2025 01:40 PM IST
Class 12 ISC Chemistry Answer Key 2025: Question Paper Distributed
The question papers are distributed among the candidates. Candidates now have 15 minutes to go through the same, and decide which section to answer first.
Feb 24, 2025 01:20 PM IST
Class 12 ISC Chemistry Answer Key 2025: Revision Question 9
Differentiate between an antiseptic and a disinfectant.
Feb 24, 2025 01:00 PM IST
Class 12 ISC Chemistry Answer Key 2025: One Hour to Go
Candidates must take their seats within the hall, the question paper will be distributed soon.
Feb 24, 2025 12:45 PM IST
ISC 12th Chemistry Answer Key 2025: Revision Question 8
A substance decomposes by following first-order kinetics. If 50% of the compound is decomposed in 120 minutes, how long will it take for 90% of the compound to decompose?
Feb 24, 2025 12:30 PM IST
ISC Class 12 Chemistry Answer Key 2025: Revision Question 7
What will be the major product obtained when 2-bromobutane reacts with alcoholic potassium hydroxide? State the type of reaction involved in it.
Feb 24, 2025 12:15 PM IST
Class 12 ISC Chemistry Answer Key 2025: Revision Question 6
Explain why transition metals and their compounds act as a catalysts.
- Physisorption decreases with an increase in temperature. Give reason.
- Why does the addition of alum purify water?
- Brownian movement stabilizes colloidal solutions. How?
Feb 24, 2025 12:00 PM IST
Class 12 ISC Chemistry Answer Key 2025: Revision Question 5
State Faraday’s first law of electrolysis. Calculate the charge required in terms of Faraday for the reduction of 1 mole of Cu2+ to Cu.
Feb 24, 2025 11:45 AM IST
Class 12 ISC Chemistry Answer Key 2025: Revision Question 4
Give one chemical test each to distinguish between the following pairs of compounds:
- Benzaldehyde and Benzoic acid
- Propanal and Propanone
Feb 24, 2025 11:30 AM IST
Class 12 ISC Chemistry Answer Key 2025: Revision Question 3
Explain why:
- PCl5 exists, but NCl5 does not.
- Fluorine is a stronger oxidising agent than chlorine.
- Bond enthalpy of F2 is less than that of Cl2.
Feb 24, 2025 11:15 AM IST
ISC 12th Chemistry Answer Key 2025: Revision Question 2
Account for the following:
- CH3CHO is more reactive with HCN than CH3COCH3.
- Carboxylic acids are stronger acids than phenol.
Feb 24, 2025 11:00 AM IST
ISC Class 12 Chemistry Answer Key 2025: Revision Question 1
Write the chemical equations to illustrate the following name reactions:
1. Wolff-Kishner reduction.
2. Aldol condensation.
3. Cannizzaro reaction.