State hund's rule.

choose one:

a. an attraction between two electrons occurs due to vibrations in the crystal lattice.

b. each electron goes into the lowest-energy orbital available.

c. the lowest-energy electron configuration of an atom has the maximum number of unpaired electrons, all of which have the same spin, in degenerate orbitals.

d. we cannot determine both the position and the momentum of an electron in an atom at the same time.

e. no two electrons in an atom can have the same set of four quantum numbers. f. electrons orbiting and protons within the nucleus of the atom have a balanced charge, excluding attraction to charged species.

C. The lowest-energy electron configuration of an atom has the maximum number of unpaired electrons, all of which have the same spin, in degenerate orbitals.

Explanation:

The Hund's rule is used to place the electrons in the orbitals is it states that:

1. Every orbital in a sublevel is singly occupied before any orbital is doubly occupied;

2. All of the electrons in singly occupied orbitals have the same spin.

So, the electrons first seek to fill the orbitals with the same energy (degenerate orbitals) before paring with electrons in a half-filled orbital. Orbitals doubly occupied have greater energy, so the lowest-energy electron configuration of an atom has the maximum number of unpaired electrons, and for the second statement, they have the same spin.

The other alternatives are correct, but they're not observed by the Hund's rule.