Define a nuclear fusion reaction. Describe the conditions for the occurrence of a nuclear fusion reaction.

(N/A) nuclear fusion reaction is a process in which two or more lighter atomic nuclei combine to form a single,heavier nucleus,accompanied by the release of a significant amount of energy.
The conditions required for a nuclear fusion reaction to occur are:
$(i)$ The temperature of the fusing nuclei must be extremely high,typically around $10^{7} \, K$,to overcome the electrostatic repulsion between the positively charged nuclei.
$(ii)$ The nuclei must be accelerated to very high speeds,often using particle accelerators or by creating high-pressure environments,to ensure they collide with sufficient kinetic energy to fuse.