Dear experts why is equation 2 given in your site, equation 1 only should be used. Because for all the questions they go by eq 1 method . They are talking something in terms of atomic mass nuclear mass. Why is that logic not applied for all qs? Why dont we ignore positron mass since q is about max k.e. of positron

m’ = Respective nuclear masses 
If atomic masses are used instead of nuclear masses, then we have to add 6 me in the case of 'Cand 5 me in the case of 'B.



$Q=E_d+E_v+E_e$

The daughter nucleus is too heavy compared to e+ and v , so it carries negligible energy.E_d =0, if the kinetic energy carried by the neutrino is minimum (zero), the positron carries maximum energy and this is equal to Q.

Regards