4. (20 points) Manometers A cylindrical column is partially filled with two liquids: mercury and hexane. The liquids are immiscible, and so two distinct layers are formed. Mercury is the densest fluid, and the specifie gravities of hexane is 0.659. The specific gravity of mercury is unknown. The hexane layer is 3.00ft thick. The mercury layer thickness is unknown. The column is closed and the headspace is pressurized to 3 psig. A pressure gauge at the bottom of the column reads 0.5 bar. a) What is the thickness of the mercury layer? (HINT: use head pressure units) b) What is the specific gravity of mercury liquid? You must show your work