Answer:
Hydrogen
Explanation:
Hydrogen is often used in fusion reactions
4 ¹₁H --> ⁴₂He + 2⁰₁e
Four hydrogen atoms undergo fusion reaction to form helium and 25 MeV( mega electron volt) of energy. Fusion reaction also occurs with isotopes of hydrogen such as deuterium and tritium.
²₁H + ²₁H --> ⁴₂He
²₁H + ³₁H --> ⁴₂He + ¹₀n
