Question

Determine the correctness or otherwise of the following Assertion [a] and Reason [r] [a]: MgCl$_2$ is used in the formulation of anti-crease finishing of cotton fabric with DMDHEU.
[r]: MgCl$_2$ is an acidic salt and acts as a catalyst.

• A. Both [a] and [r] are true and [r] is the correct reason for [a]
• B. Both [a] and [r] are true but [r] is not correct reason for [a]
• C. Both [a] and [r] are false
• D. [a] is true but [r] is false

Hint:

In Assertion-Reason type questions, carefully check if the reason not only states a true fact but also explains \textbf{why} the assertion is true. If both conditions hold, option (A) is correct.

Answer 1

The Correct Option is A

Step 1: Analyze Assertion [a]
- DMDHEU (Dimethylol Dihydroxy Ethylene Urea) is a commonly used resin for durable press or anti-crease finishing of cotton fabrics.
- During this finishing process, MgCl$_2$ is often used as a catalyst to promote cross-linking between cellulose fibers and the resin.
- Therefore, Assertion [a] is true.
Step 2: Analyze Reason [r]
- MgCl$_2$ is indeed a slightly acidic salt.
- Its acidity and catalytic properties help accelerate the cross-linking reaction of DMDHEU with cellulose.
- Thus, Reason [r] is also true.
Step 3: Check the relation between [a] and [r]
- The use of MgCl$_2$ in DMDHEU finishing is directly because of its catalytic effect (arising from its acidic nature).
- Hence, [r] is the correct explanation for [a].
Final Answer: Both [a] and [r] are true and [r] is the correct reason for [a].