Physical changes are those where new substances are not formed and the changes are, generally, visible (or can be easily observed). Boiling and melting are example of physical changes. In each of these examples, even though molecular rearrangement may take place, the identity of the substance does not change. 

Chemical changes are characterized by formation of new chemical species. Reaction of hydrogen and oxygen to generate water is a chemical change. So is rusting of iron. 

Photosynthesis is the process through which plants convert light energy into chemical energy. Here is the chemical reaction involved:

`12 H_2O + 6 CO_2 + Light -> C_6H_(12)O_6 + 6O_2 + 6H_2O`

As we can see, water and carbon dioxide combine to form glucose and oxygen. Since new chemical species are formed, photosynthesis is clearly a chemical change.

Hope this helps.

Is photosynthesis a chemical or physical process?

A chemical process is one in which compositional changes take place. In other words, new compounds are formed by chemical reaction and changes take place at elemental level (elements bond with different elements to form new compounds). Physical processes, on the other hand, do not result in formation of new compounds or new bonds. Physical processes, generally, cause observable changes, without changing the compound. Examples of physical processes include, melting, evaporation, etc. 

Photosynthesis is a chemical process, since we make new compounds. In this process, plants use carbon dioxide and water, in the presence of sunlight, and generate glucose molecules, along with oxygen. Here is the chemical equation of photosynthesis:

`6 CO_2 + 6H_2O + (sun light) -> C_6H_12O_6 + 6O_2`

Since, we are generating new compounds, photosynthesis is a chemical process. Interestingly, we are dependent on this process for food and oxygen.

Hope this helps