The kinetic energy of `alpha` - particles emitted in the decay of `""_(88)Ra^(226)` into `""_(86)Rn^(222)` is measured to be 4.78 MeV. What is the total disintegration energy or the 'Q - value of this process ?

Explanation

The standard relation between the kinetic energy of the `alpha`-particle `(KE_alpha)` and the Q-value (or total disintegration energy ) is
`KE_a=((A-4)/A).Q`
`Q=(A/(A-4)).KE_a`.
`=(226/(226-4))xx4.78` MeV= `226/222xx4.78` MeV
Q=4.865 MeV `approx` 4.87 MeV