When copper carbonate is heated, it decomposes. The reaction stops as soon as the Bunsen burner is taken away.
Which explanation is correct?
It is exothermic: heating is needed only to supply the activation energy at the start.
It is endothermic: the products have less energy than the reactants, so heat is released.
It is exothermic: removing the burner increases the activation energy of the reaction.
It is endothermic: the products have more energy than the reactants, so energy must be supplied.
106 exam-style questions on OCR GCSE Chemistry 3.2 Energetics, covering 3.2.1 Exothermic and endothermic reactions and reaction profiles and 3.2.2 Calculating energy change from bond energies. Each one has a worked solution and a mark scheme showing where the marks go.