Physics  Buoyancy
posted by Phil .
A scale reads 20.3 N when an object is not submerged in water and 20.0 N when the object is (completely) submerged in water.
What is the specific gravity of the object?

well, it has .3N of bouyancy.
that is equivalent to what volume of water?
.3=densitywater*g*volume
solve for volume
then density= weight/volume=20.3/volume
and specfic gravity= denstiy/denstiywater. 
What is the volume , in L occupied by 50.0 kg ethanol at 20 degree centimeter ? the density of ethanol at 20 degree centimeter is 0.789 g/ml ?