Answer:
2.25E18
Step-by-step explanation:
0.000045 g of Carbon x (1 mol C/ 12.01 g C) x (6.02 x 10E23 atoms / 1 mol C)
Start with the mass, then multiply it by the molar mass but put moles on the top and grams on the bottom to cancel out the grams. Then multiply it by Avogadros Constant to get atoms