When hot water is placed into an empty water bottle, the bottle keeps its shape and does not soften. What type of plastic is the water bottle made from?

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Q: (CDS-I/2019)
When hot water is placed into an empty water bottle, the bottle keeps its shape and does not soften. What type of plastic is the water bottle made from?
Which of the following are the reasons/factors for exposure to benzene pollution ? 1. Automobile exhaust 2. Tobacco smoke 3. Wood burning 4. Using varnished wooden furniture 5. Using products made of polyurethane Q. Select the correct answer using the code given below : (a) 1, 2 and 3 only (b) 2 and 4 only (c) 1, 3 and 4 only (d) 1, 2, 3, 4 and 5

question_subject: 

Science

question_exam: 

CDS-I

stats: 

0,36,80,40,26,14,36

keywords: 

{'plastic': [0, 0, 0, 1], 'thermoplastic': [0, 0, 0, 1], 'water bottle': [0, 0, 0, 1], 'empty water bottle': [0, 0, 0, 1], 'hot water': [0, 0, 0, 3], 'polyurethane': [0, 0, 0, 2], 'bottle': [0, 2, 1, 2], 'thermosetting': [0, 0, 0, 1]}

The correct answer is option 4, thermosetting plastic.

When hot water is placed into an empty water bottle, the fact that the bottle keeps its shape and does not soften suggests that it is made from thermosetting plastic.

Thermosetting plastics, also known as thermosets, are a type of polymer that undergoes a chemical reaction when heated and solidify into a permanent, rigid structure. This means that once they are set, they cannot be melted or reshaped. The process of heating thermosetting plastics causes cross-linking, which is the formation of strong chemical bonds between polymer chains.

In contrast, thermoplastic plastics, like option 1, have a lower melting point and can be melted and reshaped multiple times without any chemical change. PVC (option 2) and polyurethane (option 3) are examples of thermoplastic materials.

Therefore, option 4, thermosetting plastic, is the correct answer because it explains why the hot water does not cause the water bottle to soften or lose its shape.