The energy changes in two partial reactions are 225.3 kj and -432.0 kj. Using Hess's law, determine the combined energy change of these two partial reactions. Is the combined reaction endothermic or exothermic?

Which of the following observations indicates that an atom has neutrons? some uncharged particles are scattered by a beryllium atom when it hits a gold foil. some uncharged particles bounce back from a gold foil when it is bombarded with alpha particles. a radiation consisting of uncharged particles is emitted when alpha particles strike beryllium atoms. a radiation which attracts electrons is produced when a beryllium atom is bombarded with alpha particles.