The nuclear reaction  ${ }^2 H+{ }^2 H \rightarrow{ }^4 He$  (mass of deuteron = 2.0141 a.m.u. and mass of He = 4.0024 a.m.u.) is

Fusion reaction releasing 24 MeV energy Fusion reaction absorbing 24 MeV energy Fission reaction releasing 0.0258 MeV energy Fission reaction absorbing 0.0258 MeV energy

Fusion reaction releasing 24 MeV energy

Total mass of reactants = (2.0141) × 2 = 4.0282 amu Total mass of products = 4.0024 amu Mass defect = 4.0282 amu − 4.0024 amu = 0.0258 amu ∴ Energy released E = 931 × 0.0258 = 24 MeV