Why is the value of enthalpy of vaporization of n-pentane at 309.2 K lower than that at 298.15 K?
i) The greater volume per mole at the higher temperature indicates greater average intermolecular distances and hence weaker intermolecular forces.
ii) The higher temperature indicates greater molecular speed which weakens the intermolecular forces.
iii) i and ii
iv) None of these