37  Assertion–Reasoning

37.1 Introduction

Assertion–Reasoning (A–R) type questions test your ability to analyze a statement (Assertion) and its possible explanation (Reason).
You are required to check:
1. Whether each statement (A and R) is true or false.
2. Whether the Reason correctly explains the Assertion.

37.2 1) Format of A–R Questions

Each problem has two statements:
- Assertion (A): A factual or judgmental statement.
- Reason (R): A statement given as a possible explanation.

Your task is to select the correct option, usually among:

  1. Both A and R are true, and R is the correct explanation of A.
  2. Both A and R are true, but R is not the correct explanation of A.
  3. A is true, R is false.
  4. A is false, R is true.
  5. Both A and R are false. (sometimes included in exams)

37.3 2) Strategy to Solve

  • Step 1: Check if Assertion is true.
  • Step 2: Check if Reason is true.
  • Step 3: If both are true, check whether R logically explains A.
  • Step 4: Choose the appropriate option.

37.4 3) Examples

37.4.1 Example 1

Assertion (A): The earth revolves around the sun.
Reason (R): The sun attracts the earth by gravitational force.

  • A is true.
  • R is true.
  • R explains A.
    Answer: Option 1.

37.4.2 Example 2

Assertion (A): All prime numbers are odd.
Reason (R): 2 is the only even prime number.

  • A is false (2 is a prime but even).
  • R is true.
    Answer: Option 4.

37.4.3 Example 3

Assertion (A): The demand for umbrellas increases during rainy season.
Reason (R): During rains, people need protection from getting wet.

  • A is true.
  • R is true.
  • R explains A.
    Answer: Option 1.

37.4.4 Example 4

Assertion (A): Air is a compound.
Reason (R): Air contains a mixture of gases.

  • A is false (air is a mixture, not a compound).
  • R is true.
    Answer: Option 4.

37.5 4) Practice Questions

37.5.1 Q1

Assertion: The angles of a triangle add up to 180°.
Reason: A straight angle is equal to 180°.

37.5.2 Q2

Assertion: Demand for luxury goods increases even when price rises.
Reason: Luxury goods are considered status symbols.

37.5.3 Q3

Assertion: Plants prepare food through photosynthesis.
Reason: Photosynthesis requires sunlight, water, and carbon dioxide.

37.5.4 Q4

Assertion: Water boils at 100°C everywhere.
Reason: Boiling point depends on atmospheric pressure.

37.6 5) Suggested Answers

  • Q1: A true, R true, and R explains A → Option 1.
  • Q2: A true, R true, and R explains A → Option 1.
  • Q3: A true, R true, and R explains A → Option 1.
  • Q4: A false (not always 100°C), R true → Option 4.

37.7 Summary

  • Check truth of A and R independently.
  • If both true, check explanation link.
  • Avoid assuming external facts not in question.
  • Very useful for testing conceptual clarity in exams.