Question

what do these two changes have in common?
photosynthesis
milk going sour
select all that apply.
both are only physical changes. both are chemical changes.
both are caused by heating. both are caused by cooling.

Explanation:

Photosynthesis is a chemical change where plants use light to convert carbon dioxide and water into glucose and oxygen. Milk going sour is also a chemical change as bacteria convert lactose into lactic acid, changing the milk's composition. Both involve the formation of new substances, which is the hallmark of a chemical change.

Answer:

Both are chemical changes.