sir..here how does the value of Ps 0.98P came???
moles of benzene and toluene both are same means equal amount of both are mixed
hence we know that mole fraction is number of moles divided by total number of moles of solution
mole fraction (Xb) for benzene Nb/Nb+Nt
molefraction (Xt )for toluene Nt/Nb+Nt
Nb----no. of moles of benzene
Nt----no. of moles of toluene
given:
Nb=Nt =>Xb=Xt-------(1)
Xt+Xb=1 --------(2)
from 1&2
2Xt=1
Xt=1/2=0.5
Xt=Xb=0.5
i apologize for answer its by mistake given to you
correct answer is
pure water vapour pressure is 100% in numeric it is 1
but here given vapour pressure is 2% in numeric fraction it is 0.02
1-0.02=0.98