Definitions [3]
Define a slow change.
Changes which take place over a long period of time (hours/days/months/years) are known as slow changes.
Define a chemical change. Give two examples of the above changes.
A permanent change in which new substances are formed whose composition and properties are completely different from those of the original
substances.
Chemical change:
(i) Burning of wood.
(ii) Breathing.
Define physical change. Give two examples for the above changes.
Physical change: A temporary change in which no new substance is formed, the composition of substance remains the same, though its state, shape and size may change.
Example of physical change:
- Change of water into its vapours.
- Heating of iron rod.
