The boiling point of a liquid is that temperature at which its vapor pressure becomes equal to the atmospheric pressure. Weaker is the attractive force between the molecules of given species, more is its volatile nature and smaller is its boiling point. Attractive force ∝
1
Volatile nature
Volatile nature ∝ Vapour pressure And, Temperature for boiling point ∝
1
Volatile nature
Now draw perpendicular on x-axis from point B,A, and C and we have TC>TA>TB