The boiling point of 100 milliliters of water at sea level, vapor pressure 760 mm hg is 100oc. if, under different conditions, the boiling point of the water is 98oc, what else changed? a. the vapor pressure decreased. b. the vapor pressure increased. c. the volume of water decreased. d. the time needed to boil the water decreased.

a) the vapor pressure decreased.

If 100 milliliters of water boiled at 98oC then the vapor pressure decreased. The boiling point of water changes if we vary the vapor (atmospheric) pressure. If the pressure goes down, the boiling point drops. The opposite is also true: higher pressure means a higher boiling point.

the ideal gas law equation is as follows

pv = nrt

where p - pressure

v - volume

n - number of moles

r - universal gas constant

t - temperature

so if the pressure, volume and temperature are already known

we are left with n and r

since r is the universal gas constant that has a known fixed value then r too is known

so we are left with 'n'

once we know temperature volume and pressure

we can find the number of moles of gas present using the ideal gas law equation

this is not my own answer, this is an answer for the same question by the user blahblahmali. i do not claim ownership of this account.

there are two significant figures.