Solutions Part 1

As ∆Tb‌b=Tb−Tb‌o
Where Tb=b. pt of solution
Tbo=b.pt of solvent or
Tb=Tbo+∆Tb
NOTE : Elevation in boiling point is a colligative property, which depends upon the no. of particles. Thus greater the number of particles, greater is it elevation and hence greater will be its boiling point.
Na2SO4⇌2Na++SO42−
Since Na2SO4 has maximum number of particles (3) hence has maximum boiling point.