Question

If the reactants in a nuclear fusion have masses m₁ and m₂ and the mass of product is m₃ , then the relation between these three masses is 
1. m₃ = 2m₁ + m₂
2. m₃ = |m₁ - m₂|
3. m₃ < (m₁ + m₂)
4. m₃ > 2(m₁ + m₂)

Answer 1

Correct Answer - Option 3 : m₃ < (m₁ + m₂)

Content:

Nuclear Fusion: When two light nuclei come close to one another, within the range of attractive nuclear force, they may combine to form a bigger and stable nucleus. This process is known as nuclear fusion. The difference in mass between the reactants and products is manifested as either the release or the absorption of energy. The difference in mass is because of the difference in the binding energy of reactants and products. The process responsible for producing a large amount of energy in the star and the sun is nuclear fusion. Example of nuclear fusion -

Proton-Proton Cycle :  \({^1H} + {^1H} \rightarrow {^2H}+ e^+ +\nu\)

                                     \({^2H} + {^1H} \rightarrow {^3He}+ \gamma\)

                                    \({^2He} + {^2He} \rightarrow {^4He}+ 2{^1H}\)

 

The energy released during fusion is because of the interplay of two opposing forces: (1)Nuclear force which tries to bind proton and neutrons in the nucleus together and (2) Coulomb force which makes the protons repel each other. In the case of Lighter nuclei, the proton-proton repulsion is small in comparison to the short-range nuclear force. This is because the nucleus is sufficiently small that all the nucleons feel the short-range nuclear force and overcome coulombic repulsion. So building up nuclei from lighter nuclei leads to the release of energy indicating more stability. Whereas this fusion of the nucleus is not possible in the heavy nucleus because of greater coulombic repulsion.  

 

Explanation: 

When two nuclei undergo nuclear fusion, a lot of energy is released. This energy comes at the expanse of mass. Some mass gets converted into energy as per the relation E=mc² and hence the mass of the resulting nucleus is less than the total mass of the parent nucleus i.e.,

m₃<(m₁ + m₂)  

The correct answer is option(3)

Difference between Nuclear Fission and Nuclear Fusion-

Nuclear Fission	Nuclear Fusion
Heavier nuclei break into two or more lighter nuclei.	Lighter nuclei combine to form a heavier but stable nuclide.
It does not occur naturally.	Occurs Naturally
No external energy is required to start the process.	External energy is required to start fusion.
The energy produced is large but smaller than that in Fusion.	The energy produced is very large.