Question

A certain mass of Hydrogen is changed to Helium by the process of fusion. The mass defect in fusion reaction is 0.02866 u. The energy liberated per u is:

(given 1u = 931 MeV)

1. 2.67 MeV
2. 26.7 MeV
3. 6.675 MeV
4. 13.35 MeV

Answer 1

Correct Answer - Option 3 : 6.675 MeV

CONCEPT:

• Nuclear Fusion Reaction: The reaction in which two smaller nuclei combine to form a large nucleus is called Nuclear Fusion Reaction.
• Mass defect: The difference of mass between reactant and product is known as mass defect. 
• The energy released in Fusion: The energy released in fusion is given as 

E = Δm c²

where c is the d of light, Δm is mass defect.

• The energy released by 1 atomic unit mass is equal to 931 MeV

CALCULATION:

Given 

Mass defect = 0.2886 u

Total energy liberated = 0.2886 × 931 MeV = 26.86 MeV

We have been asked the energy liberated per unit mass

atomic mass of helium = 4 u

So, Energy liberated per unit mass  = 26.86 MeV /4

= 6.675 MeV