Periodic change : A change that repeats after a definite time interval is known as periodic change, e.g., phases of moon, heart-beat, etc.
Non-periodic change : A change that does not repeat again and again after a regular interval of time is known as non-periodic change, e.g., earthquake, flood and so on.

The changes, which can be reversed by reversing the conditions, are called reversible changes. 
For example:
(i) Conversion of ice into water by heating,
(ii) Stretching a rubber band

No, this change cannot be reversed because the toy cannot be repaired to its previous form

Slow change - ripening of fruit, fixing of curd.
Fast change - tearing a paper, grinding

Natural changes, e.g., a tree full of leaves becomes leafless, fixing of curd.

No, this change can not be reversed

The heating of iron is a reversible change. When a blacksmith first heats a piece of iron it becomes red hot. It then becomes soft and can be beaten into desired shape.

Formation of clouds is a physical change as it is phase transformation cycle of natural water from liquid to gas and then gas to liquid. Hence, the property of water never change in clouds form.

Pressure changes the shape of material, e.g. when an inflated balloon is pressed between both hands, its shape and size change.

Ice melts when it is heated. Yes, it is reversible

We cannot back iron from the rusted iron by a simple process. So, we can say that rusting of iron is an irreversible change.

From the example mentioned above, we understand that force Changes its shape and size.

In this process, the kind of changes is reversible because again we can warm it and get an iron in original form.

The two changes which cannot be reverse are
(i) Change of milk into curd.
(ii) Rusting of iron

It is an irreversible change. A tree cannot be reversed back into a plant or seed. Therefore, growth of a plant is an irreversible change.