What density causes it to sink or float?

An object will float in a fluid if its density is less than that of the fluid, while it will sink if its density is greater than the fluid's density. For example, an object with a density of 0.8 g/cm³ will float in water (1 g/cm³), whereas an object with a density of 1.2 g/cm³ will sink. The principle governing this behavior is known as buoyancy, which is influenced by the relative densities of the object and the fluid.