Question

Fusion reaction takes place at high temperature because
(A) Atoms are ionized at high temperature
(B) Molecules break up at a high temperature
(C) Nuclei break up at a high temperature
(D) Kinetic energy is high enough to overcome the repulsive force of nuclei

Answer 1

A nuclear fusion reaction is a reaction where two or more atomic nuclei come together to form different atomic nuclei with different subatomic particles. The nucleus of atoms has protons and neutrons in them. So, there is a repulsive force between them when they come together.

Complete answer:
Atoms are the smallest unit of matter that builds up chemical elements. Atoms consist of a nucleus that has neutrons and protons in them. There is an electron cloud that revolves around the nucleus that is of negative charge. The protons inside the nucleus are positively charged particles. But a neutron is not a charged particle. Hence, the nucleus region is positively charged.
A fusion reaction involves the fusing of two or more nuclei to form new nuclei. But as a nucleus is positively charged, there involves a strong repulsive force between the two nuclei. This electrostatic force must be overcome for fusion to take place. So, the fusing nuclei should have enough kinetic energy to overcome this electrostatic force. This is provided by a high temperature. So, if the nuclei have enough temperature, it will gain enough kinetic energy to overcome the electrostatic force of repulsion between the two nuclei.

Therefore, option (D) is the correct option.

Note:
Don’t confuse nuclear fusion with nuclear fission as they are two completely different processes. Both are nuclear processes but nuclear fusion is the fusing of two nuclei whereas nuclear fission is the splitting of a huge nucleus into smaller nuclei.