ISC Class 12th Chemistry Answer Key 2025: The answer key for the ISC Class 12 Chemistry exam 2025, will be released soon. This answer key will help students compare their answers and estimate their potential marks. Once the answer key is released, students can match their answers with the correct ones and evaluate their performance in the exam. This process helps students understand areas where they need improvement and where they performed well. Additionally, using the answer key allows students to learn from their mistakes and improve their preparation for future exams.
Check: ISC Class 12 Chemistry Exam Analysis 2025
Check: ISC Class 12 Chemistry Question Paper 2025
Importance of ISC Class 12th Chemistry Answer Key 2025:
- Self-Assessment: By using the answer key, students can match their answers with the correct ones. This helps them understand which questions they answered correctly and where they went wrong. It also allows students to identify their strengths and weaknesses, enabling them to prepare better for upcoming exams. Self-assessment helps students learn from their mistakes and work on improvement, boosting their confidence.
- Transparency: The answer key brings transparency to the exam process, as students can clearly see which answers were correct and which were not. This increases students' trust in the exam results, as they know the evaluation was done fairly and accurately. The answer key also shows students how correct answers should be presented, which can be helpful for future exams.
ISC Class 12th Chemistry Answer Key 2025: Key Points
Feature | Answer Key |
| Exam Date: | February 24, 2025 |
| Board Name: | ISC Board |
| https://cisce.org/ | |
| Question Paper Format: | It contains four sections and has 21questions in all.
|
| Maximum Time | 3 hours + 15 Minutes Reading time |
ISC Class 12 Chemistry Answer Key 2025
Question 1
SECTION A-14 MARKS
(A) Fill in the blanks by choosing the appropriate word(s) from those given in the [4×1]
brackets:
[+2, ethane, tetrahedral, square planar, zero, dry cell, nickel-cadmium cell, propane, Wolff-Kishner, Stephen, completely filled, incompletely filled, paramagnetic, diamagnetic]
(i)___________ is an example of a primary cell but ___________ is an example of a secondary cell.
(ii) The complex compound [Ni(CO)4] is ___________ in shape and nickel is in ________ oxidation state in this complex compound.
(iii) When acetaldehyde is treated with hydrazine and KOH in a high boiling solvent glycol,____________ is formed and the reaction is known as ________reduction.
(iv) The transition metal ions having _________ d-orbitals are colourless and _________ in nature.
Answer:
(i) dry cell is an example of a primary cell but nickel-cadmium cell is an example of a secondary cell.
(ii) The complex compound [Ni(CO)₄] is tetrahedral in shape and nickel is in zero oxidation state in this complex compound.
(iii) When acetaldehyde is treated with hydrazine and KOH in a high boiling solvent glycol, ethane is formed and the reaction is known as Wolff-Kishner reduction.
(iv) The transition metal ions having completely filled d-orbitals are colourless and diamagnetic in nature.
(B) Select and write the correct alternative from the choices given below.
(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
Answer: (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
Answer: (b) Only (P) and (R) are correct
(iii) Which one of the following alcohols is the strongest acid?
(a) Phenol
(b) Methanol
(c) Ethanol
(d) t-butyl alcohol
Answer: (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
Answer: (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
Answer: (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 nucleophile 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.
Answer: (c) Assertion is true and Reason is false.
Explanation: FeCl₃ is used in halogenation as a Lewis acid catalyst to generate the electrophile (X⁺), not a nucleophile.
(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.
Answer: (a) Both Assertion and Reason are true and Reason is the correct explanation for Assertion.
Explanation: The lanthanoid contraction causes Zr and Hf to have nearly identical atomic radii despite being in different periods.
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