What is the mass in grams of 100 atoms of carbon? (put answer in one significant figures) (To enter an answer using Scientific Notation use "e.” For example, 6.022 x 1023 would be entered
as 6.022e+23 or 6.626 x 10-34 would be entered as 6.626e-34)
[word1]

Since we are starting from the number of atoms of Sulfur, we need to know two sets of formulas:

mass  = moles × molar mass

moles = atoms ÷ Avogadro's Number

         ⇒    mass = (atoms ÷ Avogadro's Number) ×  molar mass

 mass = [(100 atoms) ÷ (6.022 × 10²³ atoms/mole)] × (12.011 g/mol)    

           = 1.99 × 10⁻²¹ g

           ≈ 2e-21         [to 1 sig fig]