Answer:
Option 4 = decomposing of water
Explanation:
Chemical change:
The changes, that occur due to change in the composition of a substance and result in a different compound is known as chemical change.
These changes are irreversible .
These changes occur due to chemical reactions .
These may not be observed with naked eye .
Example:
Combustion of fuel or wood: that oil or wood convert into energy, CO2 and ash in case of wood
Boiling of egg: that change the chemical composition of protein in the egg
The reaction of Hydrogen and oxygen:
H 2 (g) + O 2 (g) -------------------------------------> 2H 2O (l)
Physical Change
The changes that occur only due to change in shape or form but their chemical or internal composition remain unchanged.
These changes were reversible.
They have same chemical property.
These changes can be observed with naked eye.
Example
Water converting to Ice .
Water converting to gas .
In this water molecule remain the same only they rearrange themselves that change its state of mater not composition .
1 = Melting of ice
The melting of ice is physical change because water molecules are just change the state from solid to liquid and composition remain same.
2 = Boiling of water
It is also a physical change because water molecules are just change the state from liquid to gas and the molecular structure of water molecules remain same.
3 = Subliming of ice
It is physical change because ice is converted into water vapors without going through liquid phase.
4 = Decomposing of water
It is a chemical change because water molecules are split into the hydrogen and oxygen. The molecular structure is changed. New product is formed which is different from the reactant.