(a) Nuclides for which $\frac{N}{Z}$ is too small for stability can emit a positron, the electron’s antiparticle which is identical to the electron, but with positive charge. The basic process called $\beta^{+}$ decay.
$_{Z}^{A}X\ \rightarrow_{Z - 1}^{A}Y + \ e^{+} + \gamma\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ (\gamma =$neutrino$)$