What shows an atom correctly?

Joan writes four numbers on the board in standard form, and then she writes their scientific notation

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.

Correct relationship between molecular formula and empirical formula