Solar eclipse is a periodic changes. It repeats itself after a definite period of time. So it is called as periodic change.

Yes, Desalination is a process to remove the salt from the sea water. After desalinating process we will collect water from sea.

i) Temperature variation can change the substance.
ii) Every substance has a melting point. It attain the melting temperature substance can change.

\(\begin{array}{|c|l|l|} \hline \text { S.No. } &{\text { Physical change }} &{\text { Chemical change }} \\ \hline \text { 1. } & \text { No new substance are formed } & \text { New substance are formed } \\ \hline 2 . & \text { Chemical properties do not change } & \text { Chemical properties changed } \\ \hline 3 . & \text { It is a temporary action. } & \text { It is a permanent action. } \\ \hline 4 . & \text { It is a reversible reaction } & \text { It is a irreversible reaction. } \\ \hline \end{array}\)

Melting is associated when ice melts.

It is a physical change.

It is a exothermic change.

(i) Water is added to soap powder it gives heat.
(ii) Burning of wood it releases heat and light

Rotation and Revolution of the earth, Beating of the heart.

(i) Boiling of water is a physical change because it is a reversible action. No new substance is formed.
(ii) Boiling of egg is a chemical change because it is a irreversible action and new substance are formed.

Suddenly variation of temperature it shrinks so it will be cracks. so heat is obsorbed suddenly heat liberated it indicates a exothermic reaction.