When using a mercury barometer (Section 10-6), the vapor pressure of mercury is usually assumed to be zero. At room temperature mercury's vapor pressure is about 0.0015 mm-Hg. At sea level, the height h of mercury in a barometer is about 760 mm.

(a) If the vapor pressure of mercury is neglected, is the true atmospheric pressure greater or less than the value read from the barometer?

(b) What is the percent error?

(c) What is the percent error if you use a water barometer and ignore water's saturated vapor pressure at STP?