Question

When a Cs-139 atom with 55 protons undergoes TWO successive beta minus decays, what is the daughter nucleus after the second decay? Cs-139 with 55 protons Xe-139 with 54 protons O 1-139 with 54 protons La-139 with 57 protons Ba-137 with 53 protons

Answer 1

Part -A answer is

La-139 with 57 protons.

Part-B answer is

7.66 MeV

139 139 56 55 B 139 Lat 57 v te 56839 Binding energy of 19456 In bita minus decay number of protons increases nutron decreases so total nutrino remains same. B C B tute B + B² 139 La +20+2e 57 La-139 with 57 protons option is correct [19 19 mp + (56-19) mn-56.005s 186/u 19570 [1981.007276 +31x100 8664-56-0085 186]u 0.45029 U -0.450 29x931 MeV 139 So 55 Cs - 429.23 Mev 429 mer

Now binding energy per nucleon

total binding energy must be divided by number of nucleons.

= (429 MeV)/(56) = 7.66 MeV

So it is 7.66 MeV

Thanks for asking.