How do I solve assertion-reason questions in CBSE Class 10?

Judge the assertion on its own, judge the reason on its own, and only if both are true ask whether the reason explains the assertion. That order removes most confusion between the first two options. Watch for absolute words like 'always' or 'only' in either statement.

How long should I spend on a case-based question?

A rough guide is about eight to ten minutes for a four-part case, but the right figure depends on the marks and the current paper pattern. Time yourself in practice and check the latest sample paper. The routine of reading sub-questions first usually saves a minute or two.

Do I need extra books for case-based questions in Maths and Science?

Not necessarily. The NCERT textbook, the exemplar-style questions and the current CBSE sample papers are a good base. What helps most is regular timed practice with feedback on why marks were lost, more than a larger pile of material.

What share of the CBSE Class 10 paper is competency-based?

As per the pattern reported for 2026-27, about 50% is competency-based, about 20% MCQs and about 30% short and long answer. Check the current CBSE sample paper for the latest version, since patterns can be revised.

Are the examples in this guide from real CBSE papers?

No. They are teaching examples written for this article to show a method. For real question styles, use the official CBSE sample papers and previous-year papers, and check the marking scheme that accompanies them.

Case-Based and Assertion-Reason Questions in CBSE Class 10: A Practical Guide for Maths and Science

Q: What are the four options in an assertion-reason question?

A and R are both true and R is the correct explanation of A; A and R are both true but R is not the correct explanation of A; A is true but R is false; A is false but R is true. The exact wording is printed in your paper, so read it each time.

To handle a case-based question in CBSE Class 10, read the sub-questions first, then read the case once while underlining only the numbers and terms those sub-questions need, and answer each part using a single concept. To handle an assertion-reason question, judge the assertion alone, judge the reason alone, and only then decide whether the reason explains the assertion. This guide shows both routines in Maths and Science, using teaching examples written for this article and not taken from any CBSE paper.

Key Takeaways

A case-based question is a short story with several small questions attached. Each small question usually tests one familiar concept; the difficulty is in finding it.
Read the sub-questions before the case. You will then read the story looking for specific things, which saves time and cuts misreads.
In assertion-reason items, test the assertion and the reason separately before asking whether one explains the other. That simple order removes most wrong answers.
Words such as 'always', 'only', 'never' and 'all' are frequent traps. One counter-example is enough to make an 'always' statement false.
As per the pattern reported for 2026-27, about 50% of the paper is competency-based questions. Check the current sample paper. Practice on these formats is not optional.

Why this deserves its own practice

We have already written about how CBSE's competency-based questions are changing the board exam and why content revision alone does not prepare students for them. This guide takes a narrower, more practical angle. It is about what a student's eyes and pencil should do in the first ninety seconds of a case-based or assertion-reason question, in Maths and in Science. These are also the formats where a well-prepared student can gain the most from technique alone.

How to read a case-based question

A case-based question usually gives a paragraph, sometimes a table or a figure, followed by a few short sub-questions. Students often read the whole paragraph twice, slowly, then go back and forth between the story and the questions. That costs minutes and creates anxiety. Try this routine instead.

Step 1: read the sub-questions first. Note what each one asks for: a number, a comparison, a reason, a formula. You now know what to look for.
Step 2: read the case once and underline only what you need. Numbers, units, names of quantities and any condition such as 'after 5 minutes' or 'when the switch is closed'.
Step 3: name the concept for each sub-question in two or three words in the margin, for example 'AP, sum of n terms' or 'refraction, sign convention'.
Step 4: solve each sub-question independently. Do not carry a wrong answer from part one into part two if the question does not require it. Many sub-questions are designed to be independent.
Step 5: check units and sense. A negative length, an efficiency above 100% or a probability greater than 1 is a signal to recheck.

A Maths example, described in words

Imagine a case about a school garden project. The paragraph says a rectangular plot must be fenced with a fixed length of wire, that one side is along a wall so needs no wire, and that the area enclosed should reach a stated value. The sub-questions ask the student to write an expression for the second side in terms of the first, form an equation for the area, and then solve it. Nothing new is being tested here. It is a quadratic equation in disguise. A student who reads the sub-questions first sees the phrase 'form an equation' and knows a variable must be defined, so they go into the paragraph looking for two things, the fixed wire length and the target area, and ignore the decoration about who is building the garden.

A second Maths case might describe a water tank made of a cylinder with a hemisphere on top and give the radius and the height of the cylindrical part. The sub-questions could ask for the curved surface area to be painted, the volume of water the tank can hold, and the cost of painting at a given rate. Reading the questions first tells the student that formulae for cylinder and hemisphere are needed, and that the base of the cylinder is not painted if the tank stands on the ground. That one detail is where marks are often lost, and it is a reading detail, not a mathematics one.

A Science example, described in words

Imagine a Science case in which a student tests five household liquids with a pH paper and records the colours in a small table, alongside a paragraph about tooth decay and how a mouth's pH changes after a sweet snack. The sub-questions ask which liquid is most acidic, which is nearest to neutral, why a tooth-paste is basic, and what effect a low pH in the mouth has on enamel. The student does not need any hidden chapter. Each part uses Acids, Bases and Salts, and the table already holds the answers to the first two parts. Underlining the table and skipping the storytelling saves the time that a longer question will need.

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How to eliminate options in assertion-reason questions

An assertion-reason question gives two statements, an Assertion (A) and a Reason (R), followed by four standard options. A and R are both true and R is the correct explanation of A. A and R are both true but R is not the correct explanation of A. A is true but R is false. A is false but R is true. Students tend to get lost between the first two. The routine below works in three moves.

Move 1: test A on its own. Is it true? If you can think of one counter-example, it is false. Ignore R for now.
Move 2: test R on its own. Is it a true statement in general, whether or not it relates to A?
Move 3: only if both are true, test the link. Ask 'because of R, does A happen?' If the answer is 'yes, directly', pick the first option. If R is true but is about something else, pick the second.

Move 1 and Move 2 settle two of the four options before you even think about explanation. If A is true and R is false, or the other way round, you have your answer. Only when both are true do you need the third move. This order also protects you from a common trap: a well-written reason that sounds impressive and is actually false.

Three practice items, described in words

These are teaching examples written for this article. They are not from any CBSE paper. First, suppose the assertion says that the sum of any two irrational numbers is always an irrational number, and the reason says that irrational numbers are non-terminating and non-repeating decimals. The reason is a correct statement. The assertion fails because a number and its negative, such as root two and minus root two, add up to zero. So A is false and R is true. Notice that the word 'always' in the assertion was the tell, and that one counter-example finished the job.

Second, suppose the assertion says that molten sodium chloride conducts electricity, and the reason says that its ions are free to move in the molten state. Both statements are true, and the second directly explains the first. This is the first option. Third, suppose the assertion says diamond does not conduct electricity, and the reason says diamond is the hardest natural substance. Both statements are true, but hardness has nothing to do with conduction, which depends on the absence of free electrons. So the reason is true but is not the correct explanation, which makes it the second option. This third pattern is where students who skip Move 3 lose marks.

A practice routine that fits into a busy week

Ten minutes a day on assertion-reason items, five in Maths and five in Science, timed at about a minute each. Speed is part of the skill.
Two case-based questions a week in each subject, done with a stopwatch. Aim to finish a four-part case in roughly eight to ten minutes and adjust once you see the current sample paper.
An error log with four tags: misread, concept, calculation and option trap. Review it weekly. If 'misread' dominates, the fix is in your reading routine, not in more content.
One weekly full paper in board pattern, so that these formats are practised in the flow of a real exam.

Common Mistakes to Avoid

Reading the case slowly and completely before looking at any question. It uses time and produces no advantage.
Answering assertion-reason by gut feel. A statement that sounds scientific is not the same as one that is true.
Treating the reason as a hint to the assertion. Judge each separately first.
Overlooking absolutes. 'Always', 'only', 'never' and 'all' usually signal a false statement, though not every time. Test with a counter-example.
Leaving case-based sub-questions blank because part one went wrong. Many parts are independent, so attempt them all.
Skipping units and context. In a Mensuration case, whether a face is painted or not decides the answer.

Expert Tips from BuzzyBrains Academy Faculty

Founder Dilip Sah (IIT Kanpur alumnus, JEE AIR 400, 25+ years of mentoring experience) has a few rules of thumb from years of watching students face unfamiliar questions:

Ask your child to write a one-line concept tag before solving. If they cannot name the concept, they have not yet understood the question.
Have them write their own assertion-reason items. Turning an NCERT statement into a true assertion with a wrong reason is a fast test of understanding.
Review options they eliminated correctly, too. Knowing why an option is wrong builds the habit that wins marks under time pressure.

These formats are woven into every weekly mock in our 10th CBSE Maths & Science Crash Course, which is capped at 12 students per batch so that each paper can be reviewed properly. If you want to see how your child handles them under time, talk to us to check batch dates. For the chapter side of the picture, see our guides on Maths weightage and the Science revision plan.