WAEC Chemistry 2019 Paper

Concept:The sign of $\Delta H$ tells whether heat is absorbed or released during a reaction.Explanation:$\Delta H$ is the change in enthalpy of the reaction.A positive $\Delta H$ means products have more enthalpy than reactants.So the reacting system gains heat from its surroundings.A reaction that absorbs heat energy from the surroundings is called endothermic.Exothermic reactions, on the other hand, release heat and have a negative $\Delta H$.A positive $\Delta H$ does not tell whether the reaction is spontaneous or slow.Answer:B. endothermic