3.A constraint is a limitation or condition that must be satisfied by a design. For example, you may only be able to use certain materials, or you might want the device to operate at a certain speed. What was a constraint (a limitation or a condition) in this version?
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it is stable as it is in group 0 which have full outer shells of electrons

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.