What happens to a radioisotope when it undergoes nuclear decay?
a) it emits charged particles but no energy.
b) it remains stable.
c) it becomes a different element.
d) it emits neutral particles and no energy.

indium, and thallium have three electrons i think

im not exactly sure but i think its b!

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.