Answer:Pair A: Same first two energy levels filled, but second configuration has an additional orbital.
Pair B: Same first three energy levels filled, but second configuration has an additional orbital.
Pair C: First configuration represents a neutral atom, while the second represents a neutral atom with fewer energy levels filled.
Pair D: First configuration represents an ion, while the second represents an ion with fewer energy levels filled.
Pair E: Same first two energy levels filled, but second configuration represents an ion with fewer energy levels filled.
Step-by-step explanation:
In each pair, the elements represent electron configurations (E.C.) of different atoms or ions. The electron configuration describes the arrangement of electrons in an atom's energy levels or orbitals.
Pair A:
Both electron configurations in Pair A have the same first two energy levels filled: 1s²2s². The only difference is that the second electron configuration includes an additional orbital, 2p 3s².
Pair B:
Both electron configurations in Pair B have the same first three energy levels filled: 1s²2s²2p³. The only difference is that the second electron configuration includes an additional orbital, 3p³.
Pair C:
In Pair C, the first electron configuration represents a neutral atom with the first three energy levels filled: 1s²2s²2p⁶. The second electron configuration represents a neutral atom with only the first energy level filled: 1s².
Pair D:
In Pair D, the first electron configuration represents an ion with the first three energy levels filled: 1s²2s²2p⁶3s¹. The second electron configuration represents an ion with only the first two energy levels filled: 1s²2s¹.
Pair E:
In Pair E, both electron configurations have the same first two energy levels filled: 1s²2s². The only difference is that the second electron configuration represents an ion with only the first energy level filled: 1s².