1. Determinati masa moleculara, raportul atomic si raportul de masa pentru oxidul de aluminiu 2. Determinati compozutia procebtuala al hidroxidului de sofiu sau sofa cauxica, 3. Determinati ce cantitate calciu este cuprinds in 112 grame oxid de calciu 4. Determinati ce cantiate de sulf in 490 de grame de acid sulfuric

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Explanation:

the answer is c

tell me if wrong

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.