How many atoms of oxygen are present in 6.50 grams of KClO4

Question

 How many atoms of oxygen are present in 6.50 grams of KClO4

Answer 1

Use dimensional analysis:

6.50 g KClO4 x 1 mol KClO4/139 g x 6.02x10²³ molecules/mole x 4 atoms of O/molecule = 1.13x10²³ atoms