Answer
a) Ba
b) Si
c) Zn
Step-by-step explanation
The presence of unpaired electrons in an atom orbitals indicates paramagnetic properties. When no unpaired electron is observed in an atom orbitals, such an atom possesses diamagnetic properties.
Therefore, atoms in their ground states that are expected to be diamagnetic in the options are:
a) Ba
b) Si
c) Zn