A4o kg skier starts at the top of a 12 meter high slope at the bottom she is traveling 10 m/s how much energy does she lose to friction? a; 2,704jb; she dosent lose any because mechanical energy is always conservedc; 2,000jd; 4,704j

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.