Which explains why carbon is a component of so many elements?
a. it appears in more than one form
b. it is the most abundant element
c. it can react with both metals and nonmetals
d. it can form stable compounds with other elements

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.