Explanation:
Physical changes are the changes that does not lead to any change in chemical composition of a substance.
For example, mass, density, volume are all physical changes.
On the other hand, a change that leads to formation of a new compound by changing the chemical composition of reactants or combining atoms is known as a chemical change.
For example, combustion, toxicity, reactivity etc are all chemical changes.
Therefore, given changes are identified as follows.
- Coal burning : It is a combustion reaction. Hence, it is a chemical change.
- Ice melting : Physical state of water changes from solid to liquid. Hence, it is a physical change.
- mixing chocolate syrup with milk : No new compound is forming as there is no chemical reaction occurring. Hence, it is also a physical change.
- explosion of a firecracker : It shows reactivity of fire cracker. Hence, it is a chemical reaction.
- magnetizing of a screwdriver : It shows physical attraction between the magnet and screwdriver. Hence, it is a physical change.
