Final answer:
Oak wood with a density of 0.850 g/cm³ will float in water because its density is less than that of the water at 1.0 g/cm³, as explained by Archimedes' Principle.
Step-by-step explanation:
The piece of oak wood with a density of 0.850 g/cm³ will float in pure water. This is because the density of water is 1.0 g/cm³ at standard temperature and pressure, and an object will float if its density is less than that of the liquid it is placed in. Since the oak wood's density is less than the density of water, it will experience a buoyant force that is strong enough to keep it afloat. This phenomenon is explained by Archimedes' Principle, which states that the buoyant force on an object submerged in a fluid is equal to the weight of the fluid displaced by the object. Therefore, the oak wood will displace a volume of water whose weight is equal to the weight of the oak, resulting in it floating.