Question

The following question consists of two statements: Assertion (A) and Reason (R). Answer this question by selecting the appropriate option given below.
Assertion (A): Onion extract loses its smell, when it is added to baking soda solution whereas it retains its smell when added to lemon juice.
Reason (R): Onion acts as an olfactory indicator.

• A. Both A and R are true, and R is the correct explanation of A.
• B. Both A and R are true, and R is not the correct explanation of A.
• C. A is true but R is false.
• D. A is false but R is true.

Hint:

Check each statement alone first. Then ask whether the reason really explains the assertion.

Answer 1

The Correct Option is B

Step 1: Check the Assertion:
Baking soda solution is basic and lemon juice is acidic.
Onion extract keeps its smell in an acid, such as lemon juice. It loses its smell in a base, such as baking soda solution. So the assertion is TRUE.

Step 2: Check the Reason:
An olfactory indicator is a substance whose smell changes in acidic or basic solutions. Onion, vanilla essence and clove oil are common examples.
So the reason is also TRUE.

Step 3: Decide whether R explains A:
The assertion describes what we observe with onion in a base and an acid. The reason only tells the kind of substance onion is. It does not say why the smell is lost in the base or kept in the acid.
As given in the official marking scheme, R is not the correct explanation of A. So the answer is option B.

Step 4: Why the other options are wrong:
Option A is wrong because it says R is the correct explanation of A.
Option C is wrong because R is true. Onion is a well-known olfactory indicator.
Option D is wrong because A is true.

Final Answer:
A and R are both true, but R is not the correct explanation of A. This is option B. \[ \boxed{\text{B}} \]