What is the 'approximate vapor pressure (mm Hg) when liquid water boils at about 100^circ C 760 mm Hg 5 mm Hg 200 mm Hg 380 mm Hg

The approximate vapor pressure of liquid water when it boils at about is 760 mm Hg. This is because the boiling point of a liquid is defined as the temperature at which its vapor pressure equals the external atmospheric pressure. At sea level, the standard atmospheric pressure is 760 mm Hg, so water boils at this pressure when it reaches . Therefore, the correct answer is:760 mm Hg