Which of the following statements about the earliest scientific investigators of quantum tunneling can be inferred from the passage?
(a) they found it difficult to increase barrier thickness continually.(b) they anticipated the later results of chiao and his colleagues.(c) they did not suppose that tunneling particles could travel faster than light.(d) they were unable to observe instances of successful tunneling.(e) they made use of photons to study the phenomenon of tunneling.

they are all solids.

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.