Answer:
1 gm/cm^3
Step-by-step explanation:
Bouyancy is equal to the amount of fluid displaced by the object times the density of the fluid ...
I will assume this object is floating in the fluid
80% of the volume of the object = volume of fluid * density of fuid
imagine a 100 cm^3 object:
100 * .8 gm/cm^3 = 80 * density of fluid
density of fluid = 100* .8 / 80 = 1 gm/ cm^3 ( like water)