Comprehension
There are a number of changes that we come across in our day-to-day life. While some of these changes are reversible and can be observed with our eyes, some changes are not reversible and we cannot observe them solely with our eyes. These changes are classified as physical and chemical changes respectively. Chemical changes cannot easily be undone. When wood is burned, you cannot take the smoke and ash and change it back into wood. With physical changes however, you can "undo" the change. Water can be frozen into ice; the ice can be heated until it changes back into water and heated more until it changes into water vapour.
There are two types of changes occur in everyday life.
1. Physical change
2. Chemical change
Chemical changes cannot easily be undone because in this change, the structure of a substance is changed. For example: When wood is burned, you cannot take the smoke and ash and change it back into wood.
1. Physical changes are reversible.
2. In physical change, no new substances are formed.
