Write the complete symbol of:
a. The nucleus with atomic number `56` and mass number `138`
The nucleus with atomic number `26` and mass number `55`
c. The nuleus with atomic number `4` and mass number `9`

Explanation

To write the complete symbols for the given nuclei based on their atomic numbers and mass numbers, we follow a standard notation where the atomic number (Z) is written as a subscript and the mass number (A) is written as a superscript. The general format is:

\[ \text{Element Symbol} \]

\[ \text{A} \]

\[ \text{Z} \]

...