Thermosetting plastics cannot be remolded because they:
A. Are linear polymers
B. Are biodegradable
C. Have cross-linked structure
D. Melt at high temperature
Answer: Option C
Solution (By JKSSB Mock Tests)
Thermosets (e.g., Bakelite) form extensive cross-links between polymer chains, making them rigid. Heating breaks bonds but degrades, not remolds. Thermoplastics are linear/branched.
Explanation:
Ozone (O₃) has one coordinate bond; a central oxygen donates a lone pair to another oxygen. CH₄, NH₃, H₂O have ordinary covalent bonds, though NH₃ can donate a pair to form NH₄⁺.
Explanation:
Ethanol, commonly known as ethyl alcohol, has the chemical formula C₂H₅OH. Methanol is CH₃OH. Acetic acid (ethanoic acid) is CH₃COOH, and propionic acid is C₂H₅COOH. Ethanol is widely used as a solvent, in alcoholic beverages, and as a biofuel.
Explanation:
Chadwick (1932) produced highly penetrating neutral radiation by bombarding Be with α-particles, identified as neutrons. Reaction: ⁹Be + ⁴He → ¹²C + ¹n.
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