Nuclear fusion

Nuclear fusion is being researched as a possible source of unlimited clean energy on Earth, but it has not yet been achieved on a large scale.

Explain, using scientific ideas, why achieving nuclear fusion on Earth is much more difficult than in the core of stars. Include at least two physical reasons in your answer.

A student claims that nuclear fission and nuclear fusion are both potential sources of energy.

Explain the difference between fission and fusion in terms of the nuclei involved and the products formed. Then, describe why fusion produces energy only when light nuclei are used.