Question: how many carbon atoms are present in 1.0 x10 4 mol of carbon?
Answer: Well... (3 grams of carbon) x (1 mole of carbon/12 grams ) = 3/12 = 1/4 of a mole of carbon. Then... ( 1/4 of a mole) x (6.02 x 1023 atoms/mole) = approximately 1.5 x 1023 atoms.