Question

Explain how the meanings of the following terms differ, nuclear fission and nuclear fusion.

Answer 1

The reactions which bring about a change in the identity and characteristics of the atomic nucleus, mainly due to a bombarding particle, are known as nuclear reactions. These reactions are mainly of four types, nuclear fission, nuclear fusion, nuclear decay, and nuclear transmutation.

Complete step by step answer:
Nuclear fission is the phenomenon in which a relatively heavy atomic nucleus is divided into lighter nuclei is known as nuclear fission. This phenomenon can occur spontaneously in a natural way or can be induced by bombarding the nucleus with a high energy particle, which breaks down the atom into atoms with lighter nuclei.
On the other hand, Nuclear fusion is a reaction in which two or more atomic nuclei are combined to form a heavier atomic nucleus and a subatomic particle.
Difference between nuclear fission and nuclear fusion:

Nuclear fission	Nuclear fusion
Splitting of two nuclei	Combining of two nuclei
The energy released is huge	The energy released is way more than fission
The energy required is more	The energy required is less
Results in highly radioactive materials	Results in stable nuclei and less radioactive materials
Rarely occurs in nature	Occurs in stars
Requires critical mass and high energy neutrons	Requires high density and high-temperature atmospheres

Note: Nuclear fission and fusion both are energy-releasing processes, but both have different results and both require different environments. We make use of fission of nuclei of several heavy elements such as uranium, plutonium for energy production but so far, we have achieved a fusion of deuterium and tritium (two isotopes of hydrogen) only.