To determine the mass of gasoline required to fill a 100mL container, we need to consider the density of gasoline. The density of gasoline is approximately 0.73 grams per milliliter (g/mL). So, we can calculate the mass of gasoline as follows:

```

Mass of gasoline = Volume of container × Density of gasoline

Mass of gasoline = 100 mL × 0.73 g/mL

Mass of gasoline = 73 grams

```

Therefore, approximately 73 grams of gasoline would be required to fill a 100mL container.