How many marks do Assertion and Reason Questions carry in Class 10 Science board exam?

In the CBSE Class 10 Science board examination, Assertion and Reason Questions appear in Section A along with regular MCQs. Each question carries 1 mark. Typically 5 assertion-reason questions appear in the board paper, contributing 5 marks out of 80 to the total score.

Which chapters are most important for Assertion Reason in Class 10 Science?

Based on previous year CBSE board paper analysis, the most frequently tested chapters for Assertion-Reason in Class 10 Science are Chemical Reactions and Equations, Life Processes, Heredity and Evolution, Light Reflection and Refraction, Electricity, and Magnetic Effects of Electric Current.

How should students approach Assertion and Reason Questions?

Evaluate each statement independently first — do not assume R explains A just because both seem true. Check if A is true or false first. Then check if R is true or false. Only if both are true, decide whether R is the correct explanation of A. The most common mistake is choosing Option A when Option B is correct because students do not verify the explanatory relationship.

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Assertion and Reason Questions for Class 10 Science
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Q: What are Assertion and Reason Questions in CBSE Class 10 Science?

Assertion and Reason Questions consist of two statements — an Assertion (A) which is a statement of fact, and a Reason (R) which is an explanation for the assertion. Students must evaluate whether each statement is true or false, and if both are true, whether R correctly explains A. There are four standard options to choose from.

Q: What are the four options in Assertion and Reason Questions?

Option A: Both A and R are true and R is the correct explanation of A. Option B: Both A and R are true but R is NOT the correct explanation of A. Option C: A is true but R is false. Option D: A is false but R is true. Students must carefully evaluate both statements independently before deciding the relationship between them.

Q: Are these Assertion and Reason Questions for Class 10 Science free?

Yes, all assertion and reason questions on this page are completely free. Click any chapter link to access the full set of questions with answers for that chapter — no login, no subscription required.

Chapter-wise Assertion and Reason Questions for CBSE Class 10 Science with complete answers and explanations. Board examination pattern 2025–26. All 15 chapters covered — Chemistry, Biology, and Physics.

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About These Assertion and Reason Questions

This page provides chapter-wise Assertion and Reason Questions for CBSE Class 10 Science with complete answers, following the exact board examination pattern. Questions cover all 15 chapters across Chemistry (Chapters 1–5), Biology (Chapters 6–9), and Physics (Chapters 10–15). Each question consists of an Assertion (A) and a Reason (R) — students must evaluate both statements and their relationship using the standard 4-option format prescribed by CBSE.

📋 What Are Assertion and Reason Questions?

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Format and Structure

Each Assertion-Reason question consists of two statements:

Assertion (A): A statement of fact related to the chapter topic
Reason (R): A statement that may or may not explain the assertion

Students must evaluate whether each statement is individually true or false, and if both are true, whether R correctly explains A. The question carries 1 mark and appears in Section A of the CBSE Class 10 Science board paper.

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The Four Standard Options — Memorise These Exactly

Option (a): Both A and R are true and R is the correct explanation of A
Option (b): Both A and R are true but R is NOT the correct explanation of A
Option (c): A is true but R is false
Option (d): A is false but R is true

Note: There is no option where both A and R are false — if A is false, R is always true in the CBSE format.

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Marks in the CBSE Class 10 Science Board Paper

Assertion-Reason questions appear in Section A of the CBSE Class 10 Science board examination alongside regular MCQs. Each question carries 1 mark. Typically 5 assertion-reason questions appear in the board paper, contributing 5 marks out of 80 to the total score. Since they carry the same marks as regular MCQs but require more careful thinking, practising them specifically is essential.

📂 Chapter-Wise Assertion and Reason Questions for Class 10 Science

Click any chapter to access the complete set of questions with answers

⚗️ Chemistry — Chapters 1 to 5

🧬 Biology — Chapters 6 to 9

⚡ Physics — Chapters 10 to 15

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✅ How to Solve Assertion and Reason Questions — Step by Step

The most common mistakes and how to avoid them

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Step 1 — Evaluate the Assertion First, in Isolation

Read only the Assertion (A) and decide: is this statement scientifically correct or not? Do not read the Reason yet. If A is false, the answer is automatically either option (d) — go to Step 2 to check R. Many students make the mistake of reading both together and letting a true R make them assume A is also true.

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Step 2 — Evaluate the Reason Independently

Now read only the Reason (R) and decide: is this statement scientifically correct or not? Evaluate R on its own merit — not based on whether it sounds like it explains A. A Reason can be a perfectly true scientific statement but still not be the correct explanation for that specific Assertion.

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Step 3 — If Both Are True, Check the Explanatory Relationship

This is the hardest and most important step. If both A and R are true, ask: does R directly and completely explain WHY A is true? Or is R just a related true fact that does not actually explain A? The distinction between option (a) and option (b) — the most common wrong choice — depends entirely on this step.

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Most Common Mistake — Choosing (a) When the Answer is (b)

The single most common error in Assertion-Reason questions is selecting option (a) when option (b) is correct. This happens when students confirm that both statements are true but do not carefully verify whether R actually explains A or is merely a related fact. Always ask: Does R answer the question “WHY is A true?” If it explains something related but different, option (b) is correct.

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Step 4 — Use the Process of Elimination

If you are unsure whether A is true or false, use scientific reasoning to eliminate. For Science, think about what you know about the chapter topic. If A involves a law or definition, verify it precisely — often the Assertion is a slightly modified version of the correct statement, making it false. Knowing your definitions and laws precisely is the key preparation strategy for AR questions.

🎯 High Priority Chapters for Assertion-Reason in Board Exams

Based on CBSE Class 10 Science previous year board paper analysis

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Most Frequently Tested Chapters

Chapter 1 – Chemical Reactions and Equations — Types of reactions, balancing equations, oxidation-reduction concepts tested frequently

Chapter 6 – Life Processes — Photosynthesis, respiration, nutrition, transportation — concept-rich, excellent for assertion-reason format

Chapter 9 – Heredity and Evolution — Mendel’s laws, traits, evolution — statement-based evaluation fits AR format perfectly

Chapter 10 – Light Reflection and Refraction — Mirror and lens laws, image formation — laws that can be precisely stated and tested

Chapter 12 – Electricity — Ohm’s law, resistance, circuits — numerical law statements ideal for AR format

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Also Important — Do Not Skip These

Chapter 3 – Metals and Non-Metals — Properties and reactions of metals — factual statements well-suited to AR

Chapter 4 – Carbon and Its Compounds — Covalent bonding, isomers, homologous series

Chapter 13 – Magnetic Effects of Electric Current — Fleming’s rules, electromagnetic induction

Chapter 7 – Control and Coordination — Nervous system, hormones — precise definitions essential

About Assertion and Reason Questions for Class 10 Science

Assertion and Reason Questions represent one of the most intellectually demanding question formats in CBSE Class 10 Science examinations. Unlike straightforward MCQs that test recall, or Case Study questions that test application to scenarios, Assertion-Reason questions test a student’s ability to evaluate the truth and logical relationship between two scientific statements simultaneously. This requires both precise factual knowledge and clear logical reasoning — skills that can only be developed through consistent, deliberate practice.

Why Class 10 Science Is Particularly Suited to Assertion-Reason Format

CBSE Class 10 Science covers three domains — Chemistry, Biology, and Physics — each with precise laws, definitions, and cause-effect relationships. This structure makes it ideal for Assertion-Reason questions. A chemistry law like Mendeleev’s periodic law can be stated as an Assertion, with a student needing to evaluate whether the given Reason correctly explains its basis. A biological process like photosynthesis involves a sequence of causes and effects that can be tested through the assertion-reason relationship. A physics law like Ohm’s Law has precise conditions that make it possible to write true-but-not-explanatory Reasons, testing whether students understand the law deeply or just know it superficially.

The Difference Between Knowing and Understanding in Science

Assertion-Reason questions reveal a gap that most students are unaware of — the gap between knowing a fact and understanding it. A student may know that “copper is a good conductor of electricity” but not understand why — which is what the Reason tests. This is why students who rely on rote learning consistently struggle with AR questions while students who study concepts with understanding find them approachable. Regular practice with AR questions is therefore not just exam preparation — it is a diagnostic tool that helps students identify which chapters they truly understand and which they have only memorised.

CBSE Class 10 Science — All Chapters

Chapter 1: Chemical Reactions and Equations · Chapter 2: Acids, Bases and Salts · Chapter 3: Metals and Non-Metals · Chapter 4: Carbon and Its Compounds · Chapter 5: Periodic Classification of Elements · Chapter 6: Life Processes · Chapter 7: Control and Coordination · Chapter 8: How Do Organisms Reproduce · Chapter 9: Heredity and Evolution · Chapter 10: Light — Reflection and Refraction · Chapter 11: The Human Eye and the Colourful World · Chapter 12: Electricity · Chapter 13: Magnetic Effects of Electric Current · Chapter 14: Sources of Energy · Chapter 15: Our Environment

❓ Frequently Asked Questions

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What are Assertion and Reason Questions in CBSE Class 10 Science?

Each question has two statements — an Assertion (A) which is a fact, and a Reason (R) which may or may not explain A. Students evaluate whether each is true and whether R correctly explains A using four standard options. Each question carries 1 mark.

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What are the four options in Assertion-Reason Questions?

(a) Both A and R are true and R is the correct explanation of A · (b) Both A and R are true but R is NOT the correct explanation of A · (c) A is true but R is false · (d) A is false but R is true. Memorise these four options as they are identical across all chapters and all subjects.

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How many AR questions appear in the Class 10 Science board exam?

Typically 5 Assertion-Reason questions appear in Section A of the CBSE Class 10 Science board paper, each carrying 1 mark — contributing 5 marks out of 80 to the total score.

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What is the most common mistake in AR questions?

Choosing option (a) when option (b) is correct — students confirm both A and R are true but do not verify whether R actually explains A. Always ask: “Does R answer the question WHY is A true?” If not, the answer is (b), not (a).

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Are these questions free?

Yes, all Assertion and Reason Questions on this page are completely free. Click any chapter link above to access the full question set with answers for that chapter — no login or subscription needed.

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Also Check — More Class 10 Science Resources

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More Question Types — CBSE Class 10 Science

Case Study Questions — Class 10 Science MCQ Questions — Class 10 Science Previous Year Questions (PYQs) Sample Papers — Class 10 Revision Notes — Class 10 Science CBSE Class 10 Hub Page

Assertion-Reason — Other Classes and Subjects

Assertion-Reason — All Classes Hub Assertion-Reason — XAM Content More Class 10 Science AR — XAM Content AR Question Bank PDF — eBookPublisher Editable Class 10 Science Materials CBSE Class 10 Science PPTs

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