How can scientists keep track of what the atoms and molecules are doing in matter?

Drag each tile to the correct box arrange the layers not order from oldest to youngest

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.

Chemistry worksheet - i am not sure what they are asking for exactly?