In nature the chance of finding one isotope for an element is the same for all elements

2b2t

explanation:

2b2t

i'm wiling to try and you : )

it's c (engineer's do their work with mechanical stuff not on any living being)

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.