General Chemistry 1: Chemical Formulas

A white powder used in paints, enamels and ceramics has the following percentage composition: Ba (69.6%), C (6.09%), and O (24.3%). What is the empirical formula?

The nuclear power industry extracts $^6$Li but not $^7$Li from natural samples of lithium. As a result, the average molar mass of commercial samples of lithium is increased. The current abundace of the two isotopes are 7.42% and 95.58% respectively, and the masses of their atoms are 9.968 x 10$^{-24}$ g and 1.165 x 10$^{-23}$ g. What is the current molar mass of a natural sample of lithium?