An open-tube mercury manometer is used to measure the pressure in an oxygen tank. (a) When the atmospheric pressure is 990 mbar, what is the absolute pressure (in Pa) in the tank if the height of the mercury in the open tube is 27.0 cm higher than the mercury in the tube connected to the tank. Pa (b) What is the absolute pressure if the open tube mercury height is instead 4.2 cm lower than the mercury in the tube connected to the tank. Pa