Object a has a mass of 12 g and a volume of 8 cm^3. object b has a mass of 20 g and a volume of 8 cm^3. which object has a greater density and by how much? object a, by 1 gram per cubic centimeter object a, by 8 grams per cubic centimeter object b, by 1 gram per cubic centimeter object b, by 8 grams per cubic centimeter