Question

which of these is an example of a physical change?
○ a banana ripening in the air
○ hydrogen burning in the air
○ zinc reacting with an acid
○ liquid water turning into vapor

Explanation:

A physical change alters the form of a substance but not its chemical composition. Liquid water and water vapor are both H₂O, just in different physical states. The other options involve chemical reactions that create new substances: ripening involves biochemical changes, burning hydrogen produces water, and zinc reacting with acid produces zinc salt and hydrogen gas.

Answer:

liquid water turning into vapor