ICSE Class 10 Chemistry Answer Key 2025, Download PDF

ICSE Class 10 Chemistry Answer Key 2025: The answer key for the ICSE Class 10 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| ICSE  Class 10 Chemistry Exam Analysis 2025

Check| ICSE  Class 10 Chemistry Question Paper 2025

Importance of ICSE Class 10 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.

ICSE Class 10 Chemistry Exam 2025: Key Highlights

ICSE Class 10 Chemistry Answer Key 2025

Question 1.

(i): Which gas decolorises potassium permanganate (KMnO₄) solution?

Answer: (a) Sulphur dioxide

Explanation:

Sulphur dioxide (SO₂) is a reducing agent and reduces acidic potassium permanganate (KMnO₄) from purple to colourless.

(ii): Which formula represents a saturated hydrocarbon?

Answer: (b) C₅H₁₂

Explanation:

A saturated hydrocarbon (alkane) follows the general formula CₙH₂ₙ₊₂. Pentane (C₅H₁₂) fits this formula, confirming it is a saturated hydrocarbon.

(iii): The metal whose oxide can be reduced by common reducing agents:

Answer: (a) Copper
Explanation:

Copper(II) oxide (CuO) can be reduced by common reducing agents like carbon or hydrogen to form copper metal.

(iv): An organic compound has a vapor density of 22. The molecular formula of the organic compound is (Atomic weight C=12, H=1)

Answer: (c) C₃H₈

Explanation:
Vapor density (VD) = Molecular mass / 2
∴ Molecular mass = 22 × 2 = 44
The only hydrocarbon with a molecular mass of 44 is C₃H₈ (propane).

(v): In the reaction given below sulphuric acid acts as a/an:

S + 2H₂SO₄ → 3SO₂ + 2H₂O

Answer: (c) Oxidising agent

Explanation:

Sulfur (S) is oxidized to sulfur dioxide (SO₂), meaning H₂SO₄ acts as an oxidizing agent.

(vi): Assertion (A): The tendency of losing electrons increases down the Group.

Reason (R): The most reactive metal is placed at the top of Group 1.

Answer: (d) (A) is false but (R) is true.

Explanation:

The tendency to lose electrons increases down a group, so (A) should be true. However, Group 1 metals become more reactive as you go down, meaning the most reactive metal is at the bottom, not at the top.

(vii): The ore that can be concentrated by using magnetic separation:

Answer: (b) Haematite

Explanation:

Haematite (Fe₂O₃) is an iron ore that can be separated using a magnetic method due to the presence of iron.

(viii): The diagram shows bonding in the covalent molecule AB₂.

Answer: Option (d)

(ix): Which of the following options has all the compounds which are members of the same homologous series?

Answer: (a) CH₄, C₂H₆, C₃H₈

Explanation:

These compounds belong to the alkane homologous series (CₙH₂ₙ₊₂).

(x): Assertion (A): In the Contact Process SO₃ gas is not directly dissolved in water to obtain sulphuric acid.

Reason (R): Dense fog or misty droplets of sulphuric acid are formed which is difficult to condense.

Answer: (a) Both (A) and (R) are true, and (R) is the correct explanation of (A). 

Explanation:

SO₃ forms misty droplets of H₂SO₄ when dissolved in water, so it's absorbed in concentrated H₂SO₄ instead.

Q1 (xi): Identify the pair of ions with the same electronic configuration.

Given ions: Cl⁻, Li⁺, Al³⁺, K⁺

Answer: (d) Cl⁻ & K⁺

Explanation:

Cl⁻ (17 + 1 = 18 electrons)

K⁺ (19 - 1 = 18 electrons)
Both have the argon (Ar) electronic configuration.

(xii): Which pair of reactants can best produce lead (II) sulphate?

Answer: (c) Sodium sulphate + Lead nitrate 

Explanation:
Pb(NO₃)₂ + Na₂SO₄ → PbSO₄ (precipitate) + 2NaNO₃
Lead sulfate (PbSO₄) is an insoluble precipitate formed in a double displacement reaction. 

(xiii): Aqueous copper (II) sulphate is electrolysed using copper electrodes.
Which statement about the electrolysis is not correct?
(a) An oxidation reaction occurs at the positive electrode.
(b) The current is carried through the electrolyte by ions.
(c) The positive electrode loses mass.
(d) The number of copper (II) ions in the electrolyte decreases.

Answer: (d) The number of Cu²⁺ ions in the electrolyte decreases. ✅

Explanation:

In electrolysis using copper electrodes, Cu²⁺ from the anode dissolves into solution while Cu²⁺ from the solution deposits on the cathode, keeping Cu²⁺ concentration unchanged.

(xiv): X, Y & Z are three metallic atoms in successive order belonging to the same group such that atomic radii of 'X' is the smallest. Which of the three atoms is the best reducing agent?

Answer: (c) Z

Explanation: In a group, the largest atom (Z) has the weakest hold on its electrons, making it the best reducing agent.

(xv): 40 cm³ of methane (CH ₄ ) is reacted with 60 cm³ of oxygen.
The equation for the reaction is given below:

CH  ₄ + 2O  ₂ ⟶ CO  ₂ + 2H  ₂ O

All volumes are measured at room temperature.
What is the total volume of the gases remaining at the end of the reaction?

Answer: (b) 40 cm³

All answers will be available soon........

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