Question:
Which one of the following processes involve chemical reactions ?
(a) Storing of oxygen gas under pressure in a gas cylinder
(b) Liquefaction of air
(c) Keeping petrol in a china dish in the open
(d) Heating copper wire in the presence of air at high temperature.
Solution:
(d). Copper will react with oxygen present in air upon strong heating to form copper (II) oxide or cupric oxide.
