Answer:
C = chemical change, chemical property of reactivity.
Step-by-step 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:
The reaction of iron with air in the presence of water lead to the production if ion oxide which is called rusting. It is a chemical change.
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