Question

Given below are two statements:
Assertion (A): Ball milling is a top down approach of material synthesis.
Reason (R): Ball milling process converts bulk material into tiny material.

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

Hint:

Ball milling is a top-down method because it reduces bulk material into smaller particles.

Answer 1

The Correct Option is A

Concept:
Material synthesis approaches are mainly of two types: top-down and bottom-up.

Step 1: Understand top-down approach.
In top-down approach, large or bulk material is broken down into smaller particles or nanomaterials. \[ \text{Bulk material}\rightarrow \text{small particles} \]

Step 2: Check Assertion.
Ball milling breaks large particles into fine particles by mechanical impact and friction. \[ A \text{ is correct} \]

Step 3: Check Reason.
The reason says that ball milling converts bulk material into tiny material. This is correct. \[ R \text{ is correct} \]

Step 4: Check explanation.
Since converting bulk material into smaller material is exactly the meaning of top-down synthesis, Reason correctly explains Assertion. \[ \therefore \text{Correct Answer is (A)} \]