Why do apples and potatoes change colors when cut and left outside???

When the air hits hem they change colors. A little bit of lemon juice will stop it from happening!

When they get exposed to the air, it oxidizes...making it turn a funny brown color. To prevent this, you can squeeze a little lemon juice on them...or you can squeeze some orange juice over it. Really, any citrus fruit juice will work....because the citric acid is what stops the oxidation. Hope this helps! :)

The iron in the apples mix with oxygen and oxidizes. Same thing that causes iron to rust.