Which of the following processes involves a chemical reaction?
Answer and explanation
Correct answer: D. Heating copper wire in air at high temperature
- Step 1: Heating copper in air forms black copper(II) oxide (), which is a chemical reaction.
- Step 2: Storing gas under pressure, liquefaction of air, and petrol evaporation are physical phase or pressure changes.
Answer
Heating copper wire in air at high temperature.
Why not the others: Storing gas under compression involves no molecular change; liquefaction of air is a physical cooling phase transition; and petrol evaporation is a physical phase change.
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