In which isotope is the strong nuclear force not strong enough to balance electrostatic forces between protons? . a. carbon-13. b. hydrogen-2. c. neon-21. d. uranium-238

D. uranium-238

The correct answer is option D, that is, uranium-238.

Explanation:

In all the nuclei above atomic number 83, the nuclear force is not adequately strong to poise the electrostatic repulsion among the protons. The nuclei like carbon-13, hydrogen-2 and neon-21 are all stable. However, the elements like uranium-238 are radioactive and exhibit a half-life of approximately 4.5 billion years.  

In order for the atom to be stable, it should exhibit a sufficient amount of binding energy to keep its nucleus with each other perpetually. An atom that is not stable is devoid of enough amount of binding energy to sustain its nucleus perpetually, and therefore, goes through decay in order to attain stability. Uranium-238 is an illustration of such an atom that may go through decay to attain stability.