Which of the following polymers is a thermosetting plastic?
A. PVC
B. Nylon
C. Polyethylene
D. Bakelite
Answer: Option D
Solution (By JKSSB Mock Tests)
Bakelite (phenol-formaldehyde) is thermosetting; once set, it cannot be remolded. Polyethylene, PVC, and nylon are thermoplastics – they soften on heating.
Explanation:
BOD stands for Biological Oxygen Demand. It is a measure of the amount of dissolved oxygen required by microorganisms to decompose the organic matter present in a water sample. High BOD indicates severe organic pollution and poor water quality for aquatic life.
Explanation:
In a covalent bond, atoms share pairs of electrons; the shared electrons are attracted to the nuclei of both atoms, holding them together. Ionic bonds involve electrostatic attraction between oppositely charged ions.
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