Answer: 15.3 grams C
Explanation: 1 mole is 6.02x10^23 atoms. We can find the moles of C in 7.675 x 10^23 atoms of C by dividing:
(7.675 x 10^23 atoms C)/(6.02x10^23 atoms C/mole) = 1.275 moles C
The molar mass of carbon is 12g/mole. So the mass of 7.675 x 10^23 atoms is (1.275 moles C)*(12 g/mole C) = 15.3 grams.
