How are some isotopes considered radioactive

Some isotopes are stable, but others are radioactive. An isotope will be radioactive if its nuclei are unstable. Large atomic nuclei, with more than 93 protons and their associated complement of neutrons, are inherently unstable. Uranium and plutonium are examples of such elements.

succession returns a disturbed

ecosystem to a more stable state. this is also classified into two (2) types:

primary succession and secondary succession. the primary succession arises when

a new land is transformed and a bare rock has been exposed providing an environment

that can be occupied for the first time. while, secondary succession occurs

when a previously occupied environment was disturbed that kills much of all its

community

explanation: