Answer is: leaving cheese out to get moldy.
Other examples in this question are physical change, because state of matter and shape are changed.
Mold on cheese changes chemical composition, so that is chemical change.
Physical property can be observed and measured without any changes in molecular composition. The same substance is present before and after the psysical change, just with different form or state of matter.
Another examples of chemical change (chemical reaction): running a car engine, exploding fireworks, taking aspirin for a headache and digesting Thanksgiving dinner
In chemical change new substances are formed, the atoms are rearranged and the reaction is followed by an energy change.
