Answer:
10 cm³
Step-by-step explanation:
According to Archimedes, if we place an object in water, the rise of the water in mL will be the volume of the object in cm³.
Without the rock, the water measures 20 mL.
With the rock, the water measures 30 mL.
The change here is , so 10 cm³ is the volume of the rock.
Hope this helped!