Final answer:
The number of unpaired electrons in an atom's ground state can be determined by its electron configuration, following Hund's Rule. For a Be2 2- ion, the configuration would result in no unpaired electrons, making it diamagnetic. Chlorine has one unpaired electron, and so does hydrogen.
Step-by-step explanation:
When determining the number of unpaired electrons in an atom's ground state, we examine its electron configuration and how electrons are distributed in its orbitals according to Hund's Rule. In the provided examples, it is mentioned that for a certain atom, all eight electrons occupy the first four of the stated orbitals, which implies that there are no unpaired electrons in that particular scenario, hence the answer would be A) 0 unpaired electrons.
For a Be22- ion, beryllium normally has two electrons in its 1s orbital and two electrons in its 2s orbital; adding two more electrons to form the ion would mean these extra electrons would pair up in the 2s orbital. Therefore, Be22- would have no unpaired electrons and would be diamagnetic, as all electrons would be paired.
For chlorine with seven valence electrons, one is unpaired, and hydrogen always has one valence electron which is also unpaired. Therefore, chlorine has B) 1 unpaired electron, and hydrogen similarly would have B) 1 unpaired electron.