Final answer:
The thickness of the oil layer floating on water in the large open tank is 3 meters thick, according to the information provided.
Step-by-step explanation:
The question you have asked pertains to the thickness of an oil layer floating on water in a large open tank. Based on the information provided, the thickness of the oil layer is 3 meters. This can be deduced from the principles of chemistry, such as the density and immiscibility of oil and water. In real-world scenarios like the Deepwater Horizon oil spill, crude oil being less dense than water resulted in it rising to the surface, forming a layer whose thickness could vary depending on the amount spilled and the water conditions.