Question

The isotopic mass of Rn-210 is 209.989669 amu. When this nuclide decays by electron capture,

it emits 2.368 MeV.

What is the isotopic mass of the resulting nuclide?

Answer 1

Solution :-

In the electron capture process electron is converted to the neutron and neutrino

So electron is added to the nucleus so need to add up the mass of electron

converting MeV to amu.

2.368 MeV * 1 amu / 931 MeV = 0.0025435 amu

Mass of isotope = 209.989669 amu + 0.000549 amu – 0.0025435 amu

                              = 209.9876745 amu.