2.  Physical changes.
 Chemical changes.
Physical changes
Temporary changes in which no new
substances are formed are called physical
changes.
Eg:- evaporation of water, melting of ice.

3. Chemical changes
Permanent changes in which new substances
are produced are called chemical changes.
Eg:- burning of paper, rusting of iron.

4.  The reactions in which heat energy is absorbed
or released is known as thermo chemical
reactions.

5. Endothermic reactions
Chemical reactions in which heat energy is
absorbed is called endothermic reactions.

6. Exothermic reactions
Chemical reactions in which heat energy is
released is called exothermic reactions.

7. Endothermic reaction Exothermic reaction

8.  Reactions in which light energy is
absorbed or released are called
photochemical reactions.

9. Photosynthesis Photochemistry

10.  Chemical reactions in which electrical energy
is absorbed or released are called
electrochemical reactions.

11. Voltaic cell Electrolysis of water