First of all your qstn:Vapour pressure of a liquid is like. Log10P=3.54595-313.7/T +1.40655log10T T in kelvin P in mmhg, determine /\Hv as function of time and calculate its value at 80K.is not clear.But to do itin second part -->put T = 80K in the given eqn.andd get the pressure. simple.I dont understand what /\Hv is?