Chemistry

Question Analysis
This question evaluates the student's understanding of electron configurations and the application of the Aufbau principle, Pauli exclusion principle, and Hund’s rule to determine the correct electron configuration for a given element.

Key Concept Explanation
Electron configurations describe the distribution of electrons in atomic orbitals.
The Aufbau principle states that electrons fill the lowest-energy orbitals first.
The Pauli exclusion principle limits each orbital to a maximum of two electrons with opposite spins.
Hund’s rule dictates that electrons in degenerate orbitals will occupy separate orbitals with parallel spins before pairing up.

Step-by-step Solution
1. Identify the atomic number of nickel (Ni), which is 28.
2. Fill the orbitals in order of increasing energy: 1s, 2s, 2p, 3s, 3p, 4s, 3d.
3. Calculate the number of electrons in each sublevel: