How many moles of carbon atoms are there in 3 grams of carbon?

The questions asks how many moles of carbon atoms.

Molar mass is defined as the mass of one mole of a substance or in this case 6.022x1023 atoms of carbon. So the molar mass for carbon is 12.0 g/mol. Therefore the number of moles of carbon atoms is just 36/12.0 = 3.0 moles of carbon.

How many atoms are in 36 grams of Carbon?

[36 (gC) /12.0 (gC/molC)] * 6.02*10+23 (atoms C/molC) = 1.8*10+24 atoms in 36 g Carbon