The correct option is A −56
Temperature, T1=127∘C=400 K
Temperature, T2=27∘C=300 K
The normal boiling point of a liquid is the temperature at which its vapour pressure is equal to one atmosphere.
Vapour pressure at 400 K, P1=1 atm
Molar heat of vaporisation, ΔH=8.314 kJ/mol
Effect of temperature on the vapour pressure of a liquid is given by Clausius – Clapeyron equation,
ln (P21)=(83148.314)(1400 − 1300)