Question

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R
Assertion A: CMC (Sodium carboxymethylcellulose) is a oxide, which is not water soluble.
Reason R: When CMC (Sodium carboxymethylcellulose) mix with warm water to form a gel.
In the light of the above statements, choose the most appropriate answer from the options given below

• 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:

Logic Tip: CMC is cellulose (organic plant material), not an oxide (inorganic mineral). It is literally designed to dissolve in water and make a sticky gel.

Answer 1

The Correct Option is D

Concept:
CMC (Sodium carboxymethylcellulose) is a common ceramic additive used as a binder, thickener, and suspending agent in glazes and underglazes.

Step 1:
Unlike silica, alumina, or iron, CMC is not a mineral oxide. It is an organic polymer derived from cellulose (plant fiber).

Step 2:
The assertion claims CMC is an "oxide" and that it is "not water soluble." Both of these claims are completely false. It is organic, and its entire purpose in ceramics relies on its ability to dissolve in water. Thus, Assertion A is incorrect.

Step 3:
To use CMC powder, potters typically mix it with warm water. The powder hydrates, swells, and forms a thick, clear, viscous gel, which is then added to liquid glazes to help them stick to pots and prevent the heavy particles from sinking to the bottom of the bucket. Thus, Reason R is correct.

Step 4:
Because the assertion contains fundamental chemical errors while the reason describes standard studio practice accurately, Option 4 is the correct choice. \[ \boxed{\text{(4) A is not correct but R is correct.}} \]