Ratio of Mass Number to Atomic Number after Positron Emission

A positron ($\beta^+$) emission corresponds to the conversion of a nuclear proton into a neutron:
$p \rightarrow n + e^+ + \nu_e$

For ${}_{11}^{23}\text{Na}$:
${}_{11}^{23}\text{Na} \rightarrow {}_{10}^{23}\text{Ne} + {}_{+1}^{0}e + \nu_e$

• Mass number ($A$) remains unchanged: $A = 23$.
• Atomic number ($Z$) decreases by 1: $Z = 11 - 1 = 10$.

The ratio of the atomic mass (mass number) to the atomic number of the daughter nuclide is:
$\frac{A}{Z} = \frac{23}{10}$

Correct Answer: C