Describe a chemical formula give an example

A chemical formula identifies each constituent element by its chemical symbol and indicates the proportionate number of atoms of each element.

For example, the empirical formula of ethanol may be written C2H6O because the molecules of ethanol all contain two carbon atoms, six hydrogen atoms, and one oxygen atom.

the answer is:  

line graphs show patterns in data with variables that change over time; whereas, circle graphs show data as parts out of a whole (such as out of 100%).