Question

Two lithium nuclei at room temperature do not combine to form a carbon nucleus, because:

• A. A lithium nucleus is more tightly bound than a carbon nucleus.
• B. Carbon nucleus is an unstable particle.
• C. It is not energetically favorable.
• D. Coulomb repulsion does not allow the nuclei to come very close.

Answer 1

The correct option is D

Coulomb repulsion does not allow the nuclei to come very close.

The 'binding energy per nucleon' of Carbon is more than that of the Lithium. Hence two Lithium nuclei combining and forming a C-12 nucleus is energetically favourable as the binding energy is increasing. And hence energy would be released.
The two lithium nuclei which are positively charged need to come closer to get fused and to form Carbon nucleus so that nuclear force could take over and fusion could take place. But, due to Coulomb repulsion, they can't come close at room temperature. Because at room temperatures their kinetic energy is not sufficient enough to overcome the repulsion.