Pentane can be cracked in THREE different ways to produce TWO different compounds in EACH case. Show, by means of chemical equations, the THREE different ways pentane can be cracked and name the products in EACH case.

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.