2.85 x 10^22. There are 2.85 x 10^22 atoms of carbon in a diamond with a mass of 0.568 g.
(a) Use the molar mass of C to convert grams of C to moles of C
0.568 g C x (1 mol C/12.01 g C) = 0.047 30 mol C
(b) Use Avogadro’s number to convert moles of C to atoms of C
0.047 30 mol C x (6.022 x 10^23 atoms C/1 mol C) = 2.85 x 10^22 atoms C