Which of the following processes is involved in chemical reactions?

Correct option is A

The correct answer is (a) Heating copper wire in the presence of air at high temperature.
· Among the given options, the process that involves a chemical reaction is heating copper wire in the presence of air at high temperature.
· When copper is heated in the presence of air, it reacts with oxygen to form copper oxide (CuO). This is a chemical reaction because a new substance (copper oxide) is formed, and it involves a change in the chemical composition of the copper.
· The reaction can be represented as:
2Cu+O2→2CuO
This reaction shows that the original element (copper) changes chemically by combining with oxygen, forming a new compound.
Additional Knowledge:
· Melting of ice to give water: This is a physical change, not a chemical reaction. Melting ice involves a change in the state of matter from solid (ice) to liquid (water) without changing its chemical composition (H₂O remains H₂O).
· Storing of oxygen gas under pressure in a gas cylinder: This is also a physical process where oxygen gas is simply compressed into a cylinder; there is no change in its chemical structure or composition.
· Liquefaction of air: This process involves cooling air to convert it into liquid form, but it does not alter the chemical composition of the gases present in air (such as nitrogen, oxygen, etc.). It is a physical change.