A mixture is prepared by combining 25 mL ethanol (density 0.79 g mL⁻¹), 25 mL water (density 1.00 g mL⁻¹), and 25 mL hexane (density 0.66 g mL⁻¹). After vigorous shaking and complete settling, state
(a) the number of layers that will be observed and
(b) which layer will be on the top.