What is the empirical formula of a substance that contains 12.0 g of c, 2.00 g of h, and 5.33 g of o?

Empirical formula is the simplest ratio of whole numbers of components making up a compound. 
empirical formula can be calculated as follows
                      C                             H                          O
mass          12.0 g                      2.00 g                   5.33 g 
number of moles  
                  12.0 g / 12 g/mol    2.00 g / 1 g/mol       5.33 g / 16 g/mol 
                    = 1.00 mol                = 2.00 mol           = 0.333 mol
divide by the least number of moles
                   1.00 / 0.333              2.00 / 0.333          0.333/ 0.333 
                    = 3.00                     = 6.01                    = 1.00
the number of atoms 
C - 3
H - 6
O - 1
empirical formula is C₃H₆O