How many molecules of O2 are required to form 8.9 times 10^24 molescules of CO2

Question

the equation for this question is

C2H6+ O2 —> H2O + CO2
which when balanced i believe is
2C2H6 + 7O2 —> 6H2O + 4CO2

Answer 1

moles CO₂ formed = 8.9x10²⁴ molecules x 1 mole/6.02x10²³ molecules = 1.48x10^-1 moles = 0.148 moles CO₂

moles O₂ required = 0.148 moles CO₂ x 7 moles O₂/4 moles CO₂ = 0.259 moles O₂ required

molecules O₂ required = 0.259 moles O₂ x 6.02x10²³ molecules/mole = 1.56x10²³ molecules O₂