Question

Fusion reaction takes place at high temperature because:
(A) Atoms are ionised at high temperature
(B) Molecules break up at high temperature
(C) Nuclei breakup at high temperature
(D) Kinetic energy is high enough to overcome repulsion between nuclei

Answer 1

In Fusion reaction, more than one nuclei fuse together to give a different nucleus with different subatomic particles. The nucleus of an atom is always positively charged due to the presence of protons.

Complete step by step answer:

It is known to you that atoms among other things consist of protons which are positively charged. As we know, particles with the same electromagnetic charge will repel each other but protons in an atom stay together because there is a strong interaction, pulling the protons close to each other.
In Fusion process, we need to fuse the two nuclei of atoms, so we will first need to make them come in proximity and then we can think of a reaction. Now, as both nuclei of atoms are having positive charge, it is obvious that there will be repulsion between them two. Now, if we give them a high temperature, then the reaction will occur.
This happens because at high temperature, there is enough kinetic energy to overcome the repulsion and the strong interaction pulling the protons together is stronger than repulsion pushing the protons apart, the atoms will fuse together forming a new atom containing protons of both atoms we pushed together.

Therefore, from above we can conclude that option (D) is the correct option to the given question.

Note:
Remember that this fusion reaction can either be exothermic or endothermic, but we always need to give enough kinetic energy to make the reaction facile. There is a force called nuclear attraction which makes the protons in the nucleus stick together without any repulsion even though they are all positively charged.