KVPY2015PhysicsNuclear Physics
Carbon-11 decays to boron-11 according to the following formula. ₆¹¹ C ₅¹¹ B+e⁺+v_ e +0.96 MeV Assume that positrons ( e ⁺ ) produced in the decay combine with free electrons in the atmosphere and annihilate each other almost immediately. Also assume that the neutrinos ( v _ e ) are massless and do not intersect with the environment. At t =0 we have 1 pg of ₆¹² C . If the half-life of the decay process is t₀ , the ne
Options
- A8 10¹⁸ MeV
- B8 10¹⁶ MeV
- C4 10¹⁸ MeV
- D4 10¹⁶ MeV
Correct answer
B. 8 10¹⁶ MeV
Step-by-step solution
Amount decay =0.75 10⁻⁶ gm Number of atoms =0.4 10¹⁷ Energy(in nuclear reaction) =0.96 number of atoms 4 10¹⁶ MeV By E = mc ² As 1 electron from reaction annihilate by another electrons from atmosphere so Energy from annihilation =2 mc ² 4 10¹⁶ MeV Total energy =8 10¹⁶ MeV