Answer: C - Potassium (K).
Potassium has 19 electrons. The electron configuration 1s22s22p63s23p64s1 represents the arrangement of these electrons in the various energy levels and orbitals of the atom.
The first two electrons in potassium occupy the 1s orbital, followed by two electrons in the 2s orbital, and then six electrons in the 2p orbital. This gives a total of ten electrons in the first three energy levels.
The next two electrons occupy the 3s orbital, followed by six electrons in the 3p orbital. This brings the total number of electrons up to 18.
Finally, the last electron is added to the 4s orbital, giving a complete electron configuration of 1s22s22p63s23p64s1.
This electron configuration follows the Aufbau principle, which states that electrons fill the lowest available energy level or orbital first before filling higher energy levels. The electron configuration of potassium also satisfies Hund's rule, which states that electrons in the same orbital occupy individual orbitals with parallel spins before pairing up.
