The compound unstabel nucleus `._(92)^(236)U` often decays in accordance with the following reaction
`._(92)^(236)U rarr ._(54)^(140)Xe +._(38)^(94)Sr ` + other particles
During the reaction, the uranium nucleus ''fissions'' (splits) into the two smaller nuceli have higher nuclear binding energy per nucleon (although the lighter nuclei have lower total nuclear binding energies, because they contain fewer nucleons).
Inside a nucleus, the nucleons (protonsa and neutrons)attract each other with a ''strong nuclear'' force. All neutrons exert approxiamtely the same strong nuclear force on each other. This force holds the nuclear are very close together at intranuclear distances.
Why is a `._2^4He` nucleus more stable than a `._3^4Li` nulceus?

Options

A. The strong nuclear force is larger when the neutron to proton ratio is higher.
B. The laws of nuclear physics forbid a nucleus from contaning more protons than neutrons.
C. Forces other than the strong nuclear force make the lithium nulceus less stable.
D. none of these

Answer

c

Explanation

All neutrons attract each other with the same strong nuclear force. So, the strong nuclear force holds together three protons and one neutron `(._3^4Li)` just as vigourously as it holds togther two protons and two neutrons `(._2^4He)`. Specifically, protons electrostatically repel other protons, This repulsion tries to make a nucleus fly apart.Since `(._2^4He)` contains only two protons, the attractive strong nuclear forces overcome the repulsion of the protons. Hence, the nucleus holds together. But in Since `(._3^4Li)`, the mutual repulsion of the three protons overconmes the strong nuclear attractions and the nucleus falls apart (or undergoes radioactive decay into a more stable nucleus). Therefore, the answer will be (c ).