.some changes are temporary while some others are permanent

.some changes produce new substance while others do not

.some changes are natural while others are made by human beings

.some changes are desirable to us but some changes are not desirable

slow changes

.changes which take place over a long period of time (hours days month year) are known as slow changes

Examples:

1.) growth of nail and hair

2.) changes of season

3.)germination of seed

Fast changes

.changes which take place within a short period of time (second or minutes) are known as fast changes.

Example:

1.)bursting of balloon

2.)breaking of glass

3.)bursting of fire crackers

4.)burning of paper

reversible changes

.changes which can be reversed(to back the orginal state) are known as reversible changes

1.)touch me not plant (responding to touch

2.)stretching of rubber band

3.)melting of ice

irreversible

.changes which cannot be reversed or to get back the orginal state are known as irreversble changes

Example:

1.)changes of milk into

2.)digestion of food

3.)making idly from batter