Question

Problem #15 (10 points) The stability of cl with respect to alpha, beta-plus and beta-minus decay is to be determined. The following atomic masses are known: 2 15 He: 4.002603 u 32P:31.973907 u S:35.967081 u Cl: 35.968307 u 13 Ar:35.967546 u 16 36 17 38 Is the cl nucleus subject to beta-plus decay only, beta-minus decay only, beta-minus or beta- plus, alpha-decay only, or none of these? Explain why. Show your work for full credit.

Answer 1

During alpha decay a helium nucleus separated from parent nucleus hence mass decreases by 4 and atomic number decreases by 2 hence

36 32 15 Ci + a 170

During beta plus decay a proton breaks into neutron therefore mass remain same but it's atomic number decreases

$_{17}^{36}\textrm{Cl}\rightarrow _{16}^{36}\textrm{Cl}\;\;\;+\;\;\;\beta ^+$

During beta minus decay a neutron breaks into proton hence mass remain same but number of proton in nucleus increases due to which atomic number increases

$_{17}^{36}\textrm{Cl}\rightarrow _{18}^{36}\textrm{Cl}\;\;\;+\;\;\;\beta ^-$

Hence correct