(a) In an exothermic reaction the enthalpy of product is less than that of the reactants
(b) $\Delta H_{fus} = \Delta H_{subl} - \Delta H_{vap}$
(c) A reaction for which $\Delta H^\circ$ < 0 and $\Delta S$ > 0 is possible at all temperatures.
(d) $\Delta H$ is less than $\Delta E$ for combustion of carbon to carbon dioxide.
