Identify each process as endothermic or exothermic and indicate the sign of H. (a) an ice cube melting (b) nail polish remover quickly evaporating after it is accidentally spilled on the skin (c) gasoline burning within the cylinder of an automobile engine

Answer:an ice cube melting ∆H=+ve

nail polish remover quickly evaporating after it is accidentally spilled on the skin ∆H=-ve

gasoline burning within the cylinder of an automobile engine ∆H=-ve

Explanation:

In an endothermic process, such as the melting of an ice cube, heat is absorbed from the surrounding. The enthalpy change is positive. The evaporation a nail polish and burning of gasoline are exothermic processes which lead to the release of heat to the surrounding. The sign of the enthalpy change in both cases is negative.