1. (3 pts) Torricelli Barometer. As you read in $14.3, Evangelista Torricelli invented perhaps the first barometer in 1643 by filling a glass tube with mercury which was then inverted into a reservoir of mercury without letting any air into the tube. Despite being filled, whenever the inverted tube is long enough, a gap will open between the closed end of the tube at the top and the top of the mercury column in which there is a good vacuum. Po a. (1 pt) If mercury is replaced by water, what is the minimum length for the tube in order for a vacuum gap to open up? b. (1 pt) How long does it have to be if mercury is replaced by ethanol? c. (1 pt) Water and ethanol have a finite vapor pressure, so the "vacuum gap" has a vacuum no longer. At 20'C how much does this change the height h measured in the figure for both materials? Provide your source for each vapor pressure