Can someone help me with these questions, thx

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so what is the problem with your lab report and whats the subject of the lab report? i will you

ok whats the question if not i cannot you i need question and need a thing to answer

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.