Assertion and Reasoning

Assertion and Reasoning is an important reasoning ability topic where two statements are given: one is called the Assertion and the other is called the Reason You must decide whether each statement is true and whether the reason correctly explains the assertion.

Reasoning Ability Assertion and Reasoning Competitive Exams

Assertion and Reasoning is an important reasoning ability topic where two statements are given: one is called the Assertion and the other is called the Reason. You must decide whether each statement is true and whether the reason correctly explains the assertion.

What is Assertion and Reasoning?

In an Assertion and Reasoning question, two statements are given. The first statement is the Assertion, which is usually a claim or conclusion. The second statement is the Reason, which may or may not explain the assertion.

Your task is not only to check whether both statements are true, but also to check whether the reason is the correct explanation of the assertion.

Quick idea: First check whether the assertion is true. Then check whether the reason is true. Finally, check whether the reason correctly explains the assertion.

Part	Meaning	Example
Assertion	Main statement or claim	The sun rises in the east.
Reason	Statement given as explanation	The earth rotates from west to east.
Correct Explanation	Reason explains why assertion is true	Earth’s rotation explains sunrise direction.
Wrong Explanation	Reason may be true but not connected	A true fact that does not explain the assertion.

“In assertion and reasoning, truth alone is not enough; the explanation must also match.”

Reasoning Tip

Key points

Assertion is the main statement.
Reason is the explanation statement.
Both statements may be true.
Both statements may be false.
Reason may be true but not the correct explanation.
Connection between both statements is very important.

assertion reason logic explanation

Standard Answer Pattern

Most competitive exams use a fixed answer format for assertion and reasoning questions. You should understand this pattern clearly before attempting the questions.

Option	Meaning	When to Choose
A	Both Assertion and Reason are true, and Reason is the correct explanation.	Choose when both statements are true and the reason explains the assertion.
B	Both Assertion and Reason are true, but Reason is not the correct explanation.	Choose when both are true but there is no direct explanatory link.
C	Assertion is true, but Reason is false.	Choose when the main statement is correct but the reason is wrong.
D	Assertion is false, but Reason is true.	Choose when the assertion is wrong but the reason statement is correct.
E	Both Assertion and Reason are false.	Choose when both statements are incorrect.

Rule: If both statements are true, do not immediately choose option A. First check whether the reason actually explains the assertion.

Reasoning Pattern Bank

True + Correct Explanation

Assertion is true
Reason is true
Reason explains assertion

True + Not Explanation

Assertion is true
Reason is true
But relation is missing

Assertion True, Reason False

Main statement is correct
Explanation is wrong
Choose option C

Assertion False, Reason True

Main statement is wrong
Reason statement is correct
Choose option D

Tip: Always test the relationship using the word “because”. If the sentence makes logical sense, the reason may be the correct explanation.

Assertion and reasoning concept — **Assertion and Reasoning** questions test whether you can verify truth and identify correct logical explanation.

Step-by-Step Solving Method

Step	Action	Example
Step 1	Read the assertion carefully.	Assertion: Plants need sunlight for photosynthesis.
Step 2	Check whether the assertion is true or false.	This assertion is true.
Step 3	Read the reason carefully.	Reason: Sunlight provides energy for photosynthesis.
Step 4	Check whether the reason is true or false.	This reason is also true.
Step 5	Check whether the reason explains the assertion.	Yes, sunlight provides energy, so plants need sunlight.

Important: A reason can be factually true but still not be the correct explanation of the assertion. This is the most common trap.

Solved Examples

Question	Method	Answer
Assertion: The sun appears to rise in the east. Reason: The earth rotates from west to east.	Both statements are true. Earth’s west-to-east rotation explains why the sun appears to rise in the east.	A
Assertion: A square is a rectangle. Reason: A square has four equal sides.	Both statements are true. But four equal sides does not fully explain why a square is a rectangle. A square is a rectangle because it has four right angles.	B
Assertion: Plants prepare food by photosynthesis. Reason: Plants do not need sunlight for photosynthesis.	Assertion is true. Reason is false because sunlight is needed for photosynthesis.	C
Assertion: The earth is the largest planet in the solar system. Reason: Jupiter is the largest planet in the solar system.	Assertion is false. Reason is true because Jupiter is the largest planet.	D
Assertion: 5 is an even number. Reason: Even numbers are not divisible by 2.	Assertion is false because 5 is odd. Reason is also false because even numbers are divisible by 2.	E
Assertion: Water boils at 100°C at standard atmospheric pressure. Reason: Boiling point of water changes with pressure.	Both statements are true. The reason is related, but it does not directly explain why water boils at 100°C at standard atmospheric pressure.	B
Assertion: A triangle has three sides. Reason: A triangle is a polygon with three sides.	Both statements are true. The reason correctly defines and explains the assertion.	A
Assertion: An iron nail sinks in water. Reason: Iron is denser than water.	Both statements are true. The density of iron explains why the nail sinks in water.	A

Note: Use the standard option pattern consistently. Some exams may use only four options; adjust the answer key according to that exam pattern.

Common Traps and Shortcuts

Common Traps

Choosing option A only because both statements are true.
Ignoring whether the reason explains the assertion.
Accepting a reason because it sounds scientific or formal.
Confusing related information with correct explanation.
Not checking the assertion independently.
Not reading negative words such as not, never, only, and always.

Useful Shortcuts

Check assertion first, reason second.
Use the word “because” between assertion and reason.
If “Assertion because Reason” makes sense, option A may be correct.
If both are true but explanation is weak, choose option B.
Watch for absolute words such as always, never, all, and only.
Eliminate false statements before checking explanation.

Exam approach: Classify the question as both true with explanation, both true without explanation, assertion true reason false, assertion false reason true, or both false.

Practice

A) Multiple Choice Questions

Choose the correct option:
A. Both true and Reason is correct explanation
B. Both true but Reason is not correct explanation
C. Assertion true but Reason false
D. Assertion false but Reason true
E. Both false

Assertion: The moon has no light of its own.
Reason: The moon reflects sunlight.
A B C D E
Assertion: A rectangle has four right angles.
Reason: A rectangle has four sides.
A B C D E
Assertion: 9 is an odd number.
Reason: 9 is divisible by 2.
A B C D E
Assertion: Venus is the largest planet in the solar system.
Reason: Jupiter is the largest planet in the solar system.
A B C D E
Assertion: A square has four equal sides.
Reason: All sides of a square are equal.
A B C D E

B) Solve the Higher-Order Problems

Assertion: Ice floats on water.
Reason: Ice is less dense than water. (Hint: Check whether density explains floating.)
Assertion: Plants release oxygen during photosynthesis.
Reason: Oxygen is produced as a by-product of photosynthesis. (Hint: Check whether reason explains assertion.)
Assertion: All prime numbers are odd.
Reason: 2 is a prime number. (Hint: Check exception carefully.)
Assertion: Sound cannot travel in vacuum.
Reason: Sound needs a material medium to travel. (Hint: Check science logic.)
Assertion: A leap year has 366 days.
Reason: February has 29 days in a leap year. (Hint: Check whether reason explains the extra day.)

C) Match the Case with the Correct Option

Case	Correct Option / Meaning
Both true and Reason explains Assertion	Option A
Both true but Reason does not explain Assertion	Option B
Assertion true, Reason false	Option C
Assertion false, Reason true	Option D
Both Assertion and Reason false	Option E
Reason is related but not explanatory	Usually Option B

Reasoning Reminder

Assertion and Reasoning questions test both factual correctness and logical connection. The most important skill is to decide whether the reason actually explains the assertion. Related information is not always the correct explanation.

Task: Create five assertion-reason questions: one for each option type A, B, C, D, and E.

Show Suggested Answers

Multiple Choice

A
The moon has no light of its own, and it is visible because it reflects sunlight. The reason correctly explains the assertion.
B
A rectangle has four right angles, and it also has four sides. Both are true, but having four sides alone does not explain why it has right angles.
C
9 is an odd number, so the assertion is true. But 9 is not divisible by 2, so the reason is false.
D
Venus is not the largest planet, so the assertion is false. Jupiter is the largest planet, so the reason is true.
A
A square has four equal sides. The reason states the same defining property and correctly explains the assertion.

Higher-Order Problems

Ice floats on water because ice is less dense than water.
Both statements are true and reason explains assertion.
Answer = A.
Plants release oxygen during photosynthesis because oxygen is produced as a by-product.
Both statements are true and reason explains assertion.
Answer = A.
“All prime numbers are odd” is false because 2 is a prime number and it is even.
Reason is true but assertion is false.
Answer = D.
Sound cannot travel in vacuum because it needs a material medium.
Both statements are true and reason explains assertion.
Answer = A.
A leap year has 366 days because February has 29 days in a leap year.
Both statements are true and reason explains the extra day.
Answer = A.

Concept Matching

Both true and Reason explains Assertion → Option A
Both true but Reason does not explain Assertion → Option B
Assertion true, Reason false → Option C
Assertion false, Reason true → Option D
Both Assertion and Reason false → Option E
Reason is related but not explanatory → Usually Option B

Clue Explanation

In assertion and reasoning questions, check truth first and explanation second. If both statements are true, connect them using “because”. If the connection is correct, choose option A. If both are true but the reason does not explain the assertion, choose option B.

Exam tips

Check assertion independently.
Check reason independently.
Do not assume true reason means correct explanation.
Use the word “because” to test connection.
Watch for negative words like not, never, only, and all.
Choose option B when both are true but explanation is missing.

Practice MCQs

Learning Modules