The correct option is
A 370
According to Dalton's Law of partial pressure
pA=χA.Ptotal
where, pA= partial pressure of gas A in the mixture,
χA = mole fraction of gas A =Numberofmolesofgas′A′(nA)Totalnumberofmolesofgasespresentinthemixture(ntotal)
Ptotal=Total pressure of the mixture = 740 mm
Number of moles of gas A, nA=massofgas′A′(mA)Molarmassofgas′A′(MA)
Using, mO2=16g,MO2=32g/mol, mN2=28g,MN2=28g/mol and mCH4=8g,MCH4=16g/mol
Calculating number of moles of each gas, we get: nO2=0.5mol,nN2=1molandnCH4=0.5mol
Partial pressure of Nitrogen is therefore,
pN2=χN2Ptotal=10.5+1+0.5×740mm=370mm
Option B is the correct answer.