Of all the question types in CBSE Class 10 board exams, Assertion-Reason (A-R) questions are the most consistently misunderstood — and the most consistently dropped. Students who haven't practised them specifically often guess, choosing option A (both true, R explains A) for every question. This strategy scores 1 out of 4 correct on average — a dismal result for guaranteed 2-mark questions.
The good news: Assertion-Reason questions are 100% learnable. Once you understand the framework, they become some of the most predictable questions in the paper.
Understanding the A-R Question Structure
Every A-R question has the same format. Two statements are given:
- Assertion (A): A factual claim about a topic
- Reason (R): A statement that may or may not explain why A is true
The four options are always identical across all A-R questions in all subjects:
| Option | What It Means |
|---|---|
| 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 |
⚠️ Important: Option D says A is false and R is true — not both false. Many students misread option D as "both are false." There is no "both false" option in CBSE A-R questions.
The 3-Step Framework — Never Get An A-R Wrong Again
- Is Assertion (A) true or false? Evaluate the Assertion independently — ignore R completely. Is the factual claim in A correct? Mark: A true / A false.
- Is Reason (R) true or false? Now evaluate R independently — ignore A completely. Is R a correct, accurate statement? Mark: R true / R false.
- If both are true — does R explain A? This is the hardest and most important step. R must be the direct cause or mechanism behind A. A true statement about the same topic that doesn't causally explain A = Option B, not Option A.
Step 3 Is Where Most Students Fail — Examples
The difference between Option A (R explains A) and Option B (both true, but R doesn't explain A) trips up the majority of students. Here are examples:
Example 1 — From CBSE Science 2026 (Q8)
A: Bacteria that can withstand heat have better chances of survival in a heat wave.
R: Accumulation of variations in a species increases the chances of its survival in changing environment.
Analysis: A is TRUE (heat-resistant bacteria survive better in heat waves). R is TRUE (accumulated variations do improve survival chances). Does R explain A? YES — the bacteria's heat resistance is itself an example of a variation that improves survival. Answer: Option A.
Example 2 — From CBSE Science 2026 (Q9)
A: In case of iodine deficiency in our diet, there is a possibility that we might suffer from goitre.
R: One of the symptoms of goitre is swelling of neck.
Analysis: A is TRUE (iodine deficiency causes goitre). R is TRUE (swelling of neck is a symptom of goitre). Does R explain A? NO — the symptom of goitre (swelling) does not explain why iodine deficiency causes goitre. The correct explanation would be: iodine is needed by the thyroid gland; without iodine, the thyroid gland enlarges. R is merely a description of a symptom, not a causal explanation. Answer: Option B.
Common Traps in A-R Questions
Trap 1 — "R is related to A therefore R explains A."
Being related is not the same as being a causal explanation. R must be the mechanism or reason behind A, not just a fact about the same topic. Many students choose A when the answer is B because R seems relevant.
Trap 2 — Partial truth treated as full truth.
If R contains one part that's correct and one part that's wrong (e.g., "CFCs cause ozone depletion by releasing nitrogen" — correct process, wrong element), R is FALSE. Don't mark a partially true R as true.
Trap 3 — Confusing A false / R true (Option D) with both false.
CBSE has no "both false" option. If A is false and R is also false, the question is designed so that one of them is actually true — re-read both statements carefully if you find yourself thinking both are false.
Phase 2 Preparation Plan for A-R Questions
- Review all 4 A-R questions from the 2026 Science paper (Q8, Q9, and Chemistry/Physics A-R questions)
- For each one: write out "A is [true/false] because __. R is [true/false] because __. R [does/does not] explain A because __." Writing this forces you to think through all three steps rather than guessing
- Practise 3 new A-R questions per day from NCERT-based sources — CBSE typically draws A-R statements directly from NCERT text
- Time yourself: an A-R question should take no more than 90 seconds using the 3-step framework
💡 Quick Memory Aid: "A-R-E" — first check if A is true, then check if R is true, then check if R Explains A. Never skip steps. Never decide the answer before completing all three checks.
How Many A-R Questions Appear in Phase 2?
In the 2026 Phase 1 paper, Science had 2 A-R questions in Biology (Q8-Q9) plus additional A-R type questions in Chemistry and Physics. SST also frequently includes A-R questions in the MCQ section. Across a typical paper, 4-6 A-R questions worth 4-6 marks appear. Getting all of them right — which is achievable with the 3-step framework — moves you 4-6 marks ahead of students who guess.