Name chemical changes in the chemical given below boiling of water
curdling of milk
photosynthesis
melting of wax

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.

a  solution  is always transparent, light passes through with no scattering from solute particles which are molecule in size. the  solution  is homogeneous and does not settle out. a colloid is intermediate between asolution  and a  suspension. while asuspension  will separate out a colloid will not.