Question

Assertion A: PVC is a thermoplastic.
Reason R: Plasticizers are used to make PVC flexible.
In the light of the above statements, choose the most appropriate answer:

• 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:

A thermoplastic is like candle wax (melt and reset), whereas a thermoset is like a fried egg (once set, it can't be "un-fried"). PVC's chain structure makes it wax-like!

Answer 1

The Correct Option is B

Concept: Polyvinyl Chloride (PVC) is one of the most widely used synthetic polymers. Its classification and modification are core concepts in polymer technology.

Step 1: Evaluate Assertion A.
PVC is a classic thermoplastic. It consists of linear or branched chains that can be melted and reshaped multiple times because there are no permanent chemical cross-links between the chains. Thus, A is correct.

Step 2: Evaluate Reason R.
In its pure state, PVC is rigid and brittle (uPVC). To produce flexible items like hoses or shower curtains, plasticizers (like phthalates) are added to reduce intermolecular forces between chains. Thus, R is correct.

Step 3: Determine the relationship.
While both statements are true, the fact that plasticizers are used to make it flexible is not the reason $why$ PVC is classified as a thermoplastic. PVC is a thermoplastic because of its chemical structure (lack of cross-linking), regardless of whether plasticizers are added. Therefore, R is NOT the explanation for A.