Answer:
A physical property is a characteristic of a substance that can be observed or measured without changing the identity of the substance. Physical properties include color, density, hardness, and melting and boiling points. A chemical property describes the ability of a substance to undergo a specific chemical change
Explanation:
I got this from chem.libretexts.org in case you wanted to know
After one half-life, one half is remaining. After two half-lives one fourth is remaining. So that would be 25%
