If you have several different substances mixed together, like italian salad dressing, where do the most dense materials go where do the least dense materials go

If you've ever mixed water and oil together,you've probably noticed that the oil rises to the top and the water stays at the bottom-- no matter how much you try to shake them. This is because oil is less dense than water, making it float to the top. The molecules in oil are larger than those in water, so they don't pack as tightly together as they do in water. In a mixture of oil and vinegar, the oil floats on the vinegar/water mixture, while the solids sink to the bottom. So, if one material floats over another, the material on top is less dense. 

Let me know if this helps! :)

Efficiency is an action of doing something. for example when you take a test. good efficiency means you did well but bad effeciency or no effiency means you did bad.