Question

If a sample of barium contains 2.3 x 1023 atoms of barium, how many grams of barium are in the sample?

0.38 g
2.62 g
52.4 g
359.5 g

Answer 1

Always go first to moles in these sorts of questions. From moles you can go to many other unit, including mass.

You're given a number of atoms. To go to moles, divide the number of atoms by Avogadro's number.

Now that you have moles, multiply the value by the molar mass of barium. This will give you the mass!