Step-by-step explanation:
boiling of water - Physical changes
curdling of milk - Chemical changes
photosynthesis - Chemical changes
melting of wax - Physical changes
A physical change is a change that alters the physical properties of matter particularly the form and state. In many of such cases, the change is easily reversible.
Examples are boiling of water and melting of wax
A chemical change is a change in which a new kind of matter is formed. It is always accompanied by energy changes. The process is not easily reversible.
Examples are curdling of milk and photosynthesis.