Final answer:
In each pair given (Sr or Sr2+, N or N3−, Ni or Ni+, Se2− or Sr2+) the neutral atom is larger than the cation, and the anion is larger than its parent atom.
Step-by-step explanation:
When comparing the size of atoms and ions, cations are always smaller than their neutral atoms because the loss of electrons leads to a decreased electron cloud and stronger attraction from the nucleus. Conversely, anions are always larger than their neutral atoms due to the addition of electrons resulting in increased repulsion within the electron cloud and a larger radius.
- A. Sr or Sr2+: Strontium (Sr) as a neutral atom is larger than its cation form Sr2+.
- B. N or N3-: The anion N3- is larger than the neutral nitrogen atom (N).
- C. Ni or Ni+: The neutral nickel atom (Ni) is larger than its cation form Ni+.
- D. Se2- or Sr2+: The anion Se2- is larger than the cation Sr2+.
In each of the above cases, the neutral atom is larger than the cation, while the anion is larger than the neutral atom.