Question

Assertion (A): Silicones are used for waterproofing of fabrics. 
Reason (R): The repeating unit in silicones is 

• (A) and (R) are correct, but (R) is not the correct explanation of (A).
• (A) and (R) are correct, (R) is the correct explanation of (A).
• (A) is not correct but (R) is correct.
• (A) is correct but (R) is not correct.
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Hint:

- Silicones are waterproof due to their low surface energy and hydrophobic nature, not just their repeating unit.
- The repeating unit of silicones is \( Si - O - Si \), making them flexible and thermally stable.

Answer 1

The Correct Option is A

Step 1: Understanding Assertion (A)
- Silicones are widely used for waterproofing fabrics because they form a hydrophobic layer.
- This property arises due to their low surface energy and non-polarity.
- Thus, Assertion (A) is correct.
Step 2: Understanding Reason (R)
- The basic repeating unit in silicones consists of Si-O-Si linkages with organic groups (R) attached to silicon.
- The repeating unit given in the reason is correct.
Step 3: Checking Explanation Validity
- While (R) correctly describes the structure of silicones, it does not explain why silicones are used for waterproofing.
- Waterproofing occurs due to hydrophobicity, which is influenced by surface chemistry rather than just the repeating unit.
- Since (R) does not explain (A) directly, the correct answer is option (1).
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