Question

Pick the most likely member of each pair to be one of the initial fragments formed by a fission event:

(a) ${}^{\mathbf{93}}\mathbf{Sr}$or ${}^{\mathbf{93}}\mathbf{Ru}$

(b) ${}^{\mathbf{140}}\mathbf{Gd}$or ${}^{\mathbf{140}}\mathbf{I}$,

(c) ${}^{\mathbf{155}}\mathbf{Nd}$ or ${}^{\mathbf{155}}\mathbf{Lu}$.

(Hint: See Fig. 42-5 and the periodic table, and consider the neutron abundance.)

Short answer

(a) The ranking for possibilities of nuclei fragments in a fission reaction is ${}^{93}\mathrm{Ru}$.

(b) The ranking for possibilities of nuclei fragments in a fission reaction is ${}^{140}\mathrm{Gd}$

(c) The ranking for possibilities of nuclei fragments in a fission reaction is ${}^{155}\mathrm{Nd}$.

Step-by-step solution

Stability of nuclei by the ratio of proton to neutron

The ratio of the proton to neutron decides the stability of nuclei. This ratio gives the slope of figure 42-5.

Figure: 42-5

The higher the slope of the figure, most likely is the possibility of initial fragments in fission.

Identification of nuclei for most likely in the given nuclear fission reaction

(a)

The proton to neutron ratio is more for Ru than Sr, so the strontium is most likely in the fission.

Therefore, the ranking for possibilities of nuclei fragments in a fission reaction is ${}^{93}\mathrm{Ru}$.

Identification of nuclei for most likely in given nuclear fission reaction

(b)

The proton to neutron ratio is more for Gd than I, so the Gd is most likely in the fission.

Therefore, the ranking for possibilities of nuclei fragments in a fission reaction is ${}^{140}\mathrm{Gd}$.

Identification of nuclei for most likely in given nuclear fission reaction

(c)

The proton to neutron ratio is more for Lu than Nd, so the Lu is most likely in the fission.

Therefore, the ranking for possibilities of nuclei fragments in a fission reaction is ${}^{155}\mathrm{Nd}$.