2.4 x 10^21
First, calculate the number of moles of carbon you have by dividing the mass (in grams) by the atomic weight of carbon.
Atomic weight of Carbon = 12.0107
0.047 g / 12.0107 g/mol = 0.003913 mole
Now multiply by avogadro's number
0.003913 * 6.0221409 x 10^23 = 2.35646 x 10^21
Since you only have 2 significant figures, round the result to 2 significant figures
2.4 x 10^21
