A chemistry student adds an excess of calcium nitrate solution to a solution of sodium phosphate. After the precipitate has settled and was filtered, the filtrate will contain

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.