The theory of nuclear astrophysics is that all the heavy elements like uranium are formed in the interior of massive stars. these stars eventually explode, releasing these elements into space. if we assume that at the time of the explosion there were equal amount of u-235 and u-238, how long ago did the star(s) explode that released the elements that formed our earth? the present u-235/u-238 ratio is 0.0070. [the half-lives of u-235 and u-238 are 0.7 × 109 yr and 4.47 × 109 yr.]

Calculate the minimum energy required to remove one proton from the nucleus 126c. this is called the proton-removal energy. (hint: find the difference between the mass of a 126c nucleus and the mass of a proton plus the mass of the nucleus formed when a proton is removed from 126c.) express your answer with the appropriate units. emin e m i n = nothing nothing request answer part b how does the proton-removal energy for 126c compare to the binding energy per nucleon for 126c, calculated using eb=(zmh+nmn−azm)c2?