Question

Match List-I with List-II.

List - I		List - II
A.	Sol-gel Method	I.	Top-down approach
B.	Ball Milling	II.	Thin film by rotation
C.	Chemical Vapour Deposition	III.	Bottom-up wet chemical method
D.	Spin Coating	IV.	Film growth from vapour phase

• A. A-III, B-I, C-IV, D-II
• B. A-I, B-III, C-II, D-IV
• C. A-IV, B-II, C-I, D-III
• D. A-II, B-IV, C-III, D-I

Hint:

Sol-gel is bottom-up, ball milling is top-down, CVD uses vapour phase, and spin coating uses rotation.

Answer 1

The Correct Option is A

Concept:
Material synthesis methods may be top-down or bottom-up. Thin film methods are also classified according to how material is deposited on a substrate.

Step 1: Sol-gel method.
Sol-gel is a bottom-up wet chemical method in which molecular precursors form sol and then gel. \[ A\rightarrow III \]

Step 2: Ball milling.
Ball milling breaks large particles into smaller particles, so it is a top-down approach. \[ B\rightarrow I \]

Step 3: Chemical vapour deposition.
CVD deposits material on a substrate from vapour phase chemical reactions. \[ C\rightarrow IV \]

Step 4: Spin coating.
Spin coating forms thin films by spreading solution on a rotating substrate. \[ D\rightarrow II \] Therefore: \[ A-III,\ B-I,\ C-IV,\ D-II \] \[ \therefore \text{Correct Answer is (A)} \]