Mass percentage of Fe=69.9%
Mass percentage of O=100%−69.9%=30.1%
Number of moles of Fe=5669.9=1.248
Number of moles of O=1630.1=1.881
Molar ratio of Fe:O=1.248:1.881
Dividing by the smallest value, the ratio is 1.2481.248:1.2481.881=1:1.5
Multiplying by 2 to get the simplest whole number ratio, we get 2:3.
The empirical formula is Fe2O3.
Answer: Fe2O3