2.85 × 10^22. A diamond with a mass of 0.568 g contains
2.85 × 10^22 atoms C. 
Diamond is a form of pure carbon. 
a) Convert grams of C to moles of C 
Moles of C = 0.568 g C × (1 mol C/12.01 g C) = 0.047 29 mol C 
b) Convert moles of C to atoms of C 
Atoms of C = 0.047 29 mol C × (6.022 × 10^23 atoms C)/(1 mol C)
= 2.85 × 10^22 atoms C