Which one of the following is an example of chemical change?
- Burning of paper
- Magnetization of soft iron
- dissolution of cane sugar in water
- Preparation of ice cubes from water
Chemical change results in the formation of new chemical substances. Physical change rearranges molecules but doesn't affect their internal structures.
In magnetizing of soft iron, there is realignment of iron atoms, but no real change within the iron atoms themselves. In dissolving of sugar in water, sugar molecules are dispersed within the water, but the individual sugar molecules are unchanged. In preparation of ice cubes from water, water molecules are forced together when liquid changes to solid, but the molecules are still H2O.
Burning of paper is combustion. It represents a chemical reaction whereby the carbon compounds in the paper are oxidized into different chemicals like carbon dioxide and water vapor. Other examples of chemical change are iron rusting (iron oxide forms), gasoline burning (water vapor and carbon dioxide form).
The correct option is A.