CBSE Class 10 Case-Based Questions (CBQ) Explained — With Real Worked Examples

By StudyOS · 2026-09-09

Case-Based Questions (CBQ) are the format students have the least practice with, because they're the newest — introduced as CBSE shifted toward competency-based assessment, and there's far less real prep material for them online than for ordinary MCQs. A CBQ gives you a passage — a scenario, a short experiment, a data snippet — and then 3 to 4 sub-questions built on it. Get the passage wrong and every sub-question built on it goes wrong with it. Here's how the format actually works, with real examples.

What a CBQ actually looks like

Every CBQ has two parts: a short passage describing an unfamiliar situation (not something memorized straight from the textbook), followed by 3-4 one-mark MCQ-style sub-questions. Some sub-questions test whether you understood the passage itself; others test whether you can apply the actual chapter concept to the scenario described. A few sub-questions build on each other — get an early one wrong and a later one that depends on it goes wrong too.

Worked example 1 — Science: Chemical Reactions and Equations

A chemistry teacher conducted an experiment where students burned magnesium ribbon in air and collected the white ash formed. The magnesium ribbon, initially silver in colour, burned with a dazzling white flame. The collected ash was white and appeared to have increased in mass compared to the original ribbon. The word-equation was: Magnesium + Oxygen → Magnesium oxide.

Q1. What is the correct chemical equation for the burning of magnesium in air?
(A) Mg + O → MgO   (B) 2Mg + O₂ → 2MgO   (C) Mg + O₂ → MgO₂   (D) Mg + O₂ → MgO

Answer: (B). The word-equation in the passage tells you the reactants and product — turning it into a balanced chemical equation is the actual chapter skill being tested, not the scenario itself.

Q2. Which observation in this experiment indicates a chemical reaction has definitely taken place?
(A) Only the colour change   (B) Only the dazzling flame   (C) Both the colour change and the formation of a new substance   (D) The change in physical shape

Answer: (C). This is the sub-question that actually tests passage comprehension — it wants you to identify which of the passage's own details are genuine evidence of a chemical change, not just visually dramatic.

Worked example 2 — Maths: Real Numbers

A school wants to distribute 120 pens and 90 pencils equally among students, so that each student gets the same number of pens and the same number of pencils, with none left over. 120 = 2³ × 3 × 5 and 90 = 2 × 3² × 5.

Q1. What is the HCF of 120 and 90?
(A) 15   (B) 20   (C) 30   (D) 60

Answer: (C) 30 — take the lowest power of every prime factor common to both: 2¹ × 3¹ × 5¹ = 30.

Q2. How many pens will each student receive?
(A) 2   (B) 3   (C) 4   (D) 5

Answer: (C) 4 — this is exactly the sub-question that chains off the previous one: the maximum number of students is the HCF (30), so pens per student = 120 ÷ 30 = 4. Get the HCF wrong and this answer is wrong too, even though the arithmetic here is simple.

Worked example 3 — Social Science: Resources and Development

A survey in a village called Sundarpur found that 60% of households threw agricultural waste into open spaces, 25% used it as animal feed, and only 15% composted it — residents were unaware composting could increase soil fertility. After a community education program, 70% of households began composting within six months.

Q1. What was the main reason most households initially threw away agricultural waste?
(A) They lacked the technology to process it   (B) They were unaware of the benefits of composting and sustainable resource use   (C) Government regulations forced it   (D) The waste had no economic value

Answer: (B). The passage never mentions technology or regulation — it explicitly says the villagers "were unaware." Case-based questions reward reading for what the passage actually states over what sounds plausible.

Q2. Which component of resource planning was primarily lacking before the survey?
(A) Institutional awareness and education   (B) Identification of resources   (C) Advanced technology   (D) Government support

Answer: (A). This sub-question asks you to map the scenario back onto the chapter's own framework — resource planning has named components (identification, technology, institutions), and the case is a textbook example of an institutional/awareness gap, not a technology one.

The actual strategy

1. Read the passage once for the scenario only — don't hunt for an answer yet. You're extracting what's actually happening: what changed, what numbers or facts are given, what the outcome was.
2. Identify which chapter concept the passage is really testing, stripped of its story dressing. A village composting story is a resource-planning question; a burning-magnesium story is a chemical-equation question.
3. Answer each sub-question on its own facts — most are independently gradable, so one wrong answer doesn't have to sink the rest.
4. Watch for sub-questions that visibly build on an earlier one (a "how many X" question that depends on a number from an earlier sub-question). If that shared number is wrong, fix it before trusting anything built on it.

Want the Assertion-Reason format broken down the same way? Read how CBSE Assertion-Reason questions work, or see the full Class 10 chapter-wise notes and MCQs breakdown.