Question

1. provide 1 missing symbol and 4 numbers ( symbolizes a metastable nucleus) 114 in → 114 in +

Explanation:

Step1: Recall nuclear - decay conservation laws

In nuclear reactions, the total atomic number (subscript) and the total mass number (superscript) are conserved. The metastable indium - 114 nucleus ($^{114*}_{49}\text{In}$) decays to normal indium - 114 ($^{114}_{49}\text{In}$). The difference is the emission of a gamma ray.

Step2: Write the decay equation

The decay of a metastable nucleus often involves the emission of a gamma ray ($\gamma$). The mass number and atomic number of a gamma ray are 0. The decay equation is $^{114*}_{49}\text{In}
ightarrow^{114}_{49}\text{In}+\gamma$. The four numbers can be considered as the mass number and atomic number of the initial and final indium nuclei. The atomic number of indium is 49.

Answer:

The missing symbol is $\gamma$. The four numbers are 114 (mass number of initial In), 49 (atomic number of initial In), 114 (mass number of final In), 49 (atomic number of final In)