Which agent of erosion can create a limestone cave?
a. freezing and melting ice
b. growing plant roots
c. acidic water
d. strong wind

Which of the following is an example of physical change not a chemical change? a) a log gives off heat and light as it burns. b) a tree stores energy from the sun in its fruit. c) a penny lost in the grass slowly changes color. d) a water pipe freezes and cracks on a cold night.