Select the correct answer from each drop-down menu. Complete the sentences to explain what’s happening at different portions of the heating curve. Particles of the substance have the most kinetic energy when the substance is . The part of the graph that represents where the substance has the least amount of potential energy is labeled .

50.23 i believe is correct but don't quote me on that.

chemical changes occur when a substance combines with another to form a new substance, called chemical synthesis or, alternatively, chemical decomposition into two or more different substances. these processes are called chemical reactions and, in general, are not reversible except by further chemical reactions. some reactions produce heat and are called exothermic reactions and others may require heat to enable the reaction to occur, which are called endothermic reactions. understanding chemical changes is a major part of the science of chemistry.