Answer: Natural abundance is directly proportional to stability. More is the natural abundance, more is the stability.
Explanation: Natural abundance refers to the abundance of isotopes of a chemical element which are naturally found on earth.
The isotopes which are more stable are more abundant as compared to the ones which are less stable. As the less stable ones will have small value of half life and thus would decompose more readily to more stable products by radioactive decay.
Uranium exists as three naturally occuring isotopes; [tex]^{238}\textrm{U}[/tex], [tex]^{235}\textrm{U}[/tex] and [tex]^{234}\textrm{U}[/tex] with natural abundance of about 99%, 0.7% and 0.005% respectively. Thus [tex]^{238}\textrm{U}[/tex] is the most stable isotope of Uranium and has highest natural abundance.
