∆E=mc*2=0.0286×931=26.68 Mev

Energy liberated per u= 26.68/4
= 6.675Mev

Mass Defect:
The mass defect, denoted by Δm, is the difference between the mass of the reactants and the mass of the products in a nuclear reaction. In the case of fusion, the reactant is hydrogen and the product is helium.

Given mass defect = 0.02866 u

Conversion:
1 atomic mass unit (u) is equivalent to 931 MeV (mega-electron volts).

Calculating Energy Liberated:
To calculate the energy liberated per unit mass, we need to multiply the mass defect by the conversion factor (931 MeV/u).

Energy liberated per u = Δm * 931 MeV/u

Energy liberated per u = 0.02866 u * 931 MeV/u

Energy liberated per u ≈ 26.7 MeV

Therefore, the correct answer is option 4) 26.7 MeV.

Explanation:
During the fusion reaction of hydrogen to form helium, a small amount of mass is lost due to the conversion of mass into energy. This lost mass is known as the mass defect. The energy liberated per unit mass is given by the mass defect multiplied by the conversion factor.

In this case, the mass defect is given as 0.02866 u. Multiplying this value by the conversion factor of 931 MeV/u gives us the energy liberated per unit mass, which is approximately 26.7 MeV.

This means that for every atomic mass unit of hydrogen that undergoes fusion to form helium, approximately 26.7 million electron volts of energy is released. This energy is the result of the conversion of mass into energy according to Einstein's famous equation, E=mc².

Summary:
The energy liberated per unit mass in a fusion reaction is calculated by multiplying the mass defect by the conversion factor of 931 MeV/u. In this case, the mass defect is given as 0.02866 u, resulting in an energy liberated per unit mass of approximately 26.7 MeV.