Oil is more dense than water. How will this affect the weight of objects that will float on it?

Oil is more dense than alcohol, but less dense than water. The molecules that make up the oil are larger than those that that make up water, so they cannot pack as tightly together as the water molecules can. They take up more space per unit area and are less dense.

Green is technically every other color but green but the other wavelengths of the other colors get absorbed by the object and the wavelength of the color green gets reflected