Answer:
7.6410^-14 grams N2O4
Step-by-step explanation:
I will assume that "contains a billion (1.00 × 10º)" is meant to read "(contains a billion (1.00 × 10^9)."
One mole of anything contain 6.02x10^23 particles of that thing (atoms, molecules, paper clips, suns, etc.). If there are 1.00x10^9 particles of N2O4, we have:
(1.00x10^9 particles N)/(6.02x10^23 particles/mole) = 1.66x10^-15 mole of N atoms
Each mole of N2O4 contains 2 moles of N atoms:
(1 mole N2O4)/(2 moles N atoms)
(1.66x10^-15 mole of N atoms)*(1 mole N2O4)/(2 moles N atoms) =
8.31x10^-16 moles N2O4
The molar mass of N2O4 is 92.01 g/mole.
(8.31x10^-16 moles N2O4)*(92.01 g/mole) = 7.6410^-14 grams N2O4