Which of the following is a molecule of an element?
A. H₂O
B. CO₂
C. NaCl
D. O₃
Answer: Option D
Solution (By JKExamLibrary)
Ozone (O₃) is a molecule consisting of three oxygen atoms, all of the same element. H₂O and CO₂ are compounds; NaCl is an ionic compound (not a discrete molecule). O₂ is also a molecule of an element.
Explanation:
PVC (polyvinyl chloride) is a polymer of vinyl chloride (CH₂=CHCl). It is used in pipes, electrical insulation, and flooring. It can be rigid (uPVC) or flexible with plasticizers. It is a thermoplastic. Chlorate/carbon/carbide are not correct expansions.
Explanation:
Roasting converts sulfide ores to oxides by heating in excess air: 2ZnS + 3O₂ → 2ZnO + 2SO₂. Calcination is for carbonates; leaching for others.
Explanation:
Mg goes from 0 to +2 oxidation state, losing electrons – oxidized. Oxygen is reduced (0 to -2). This is a combustion/combination redox reaction.
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