Select the set of quantum numbers that represents each electron in a ground‑state Be atom. n = 2,? = 0, m? = 0, m s = - 1 2 n = 1,? = 0, m? = 0, m s = + 1 2 n = 2,? = 0, m? = 0, m s = + 1 2 n = 2,? = 1, m? = 0, m s = - 1 2 n = 1,? = 0, m? = - 1, m s = + 1 2 n = 1,? = 0, m? = 0, m s = - 1 2 n = 2,? = 0, m? = 0, m s = - 1 n = 2,? = 1, m? = 1, m s = + 1 2

n: 1, ℓ: 0, ml: 0, ms:+1/2

n: 1, ℓ: 0, ml: 0, ms:-1/2

n: 2, ℓ: 0, ml: 0, ms:+1/2

n: 2, ℓ: 0, ml: 0, ms:-1/2

Explanation:

Beryllium has 4 electrons and its electron configuration is 1s² 2s².

The principal quantum number (n) describes the level of energy. Then, the first two electrons have n = 1, and the second 2 electrons have n = 2.

The azimuthal number (ℓ) describes the subshell of energy. All the 4 electrons are in s subshells, which correspond to ℓ = 0.

The magnetic quantum number (ml) describes the orbital of the subshell. The s subshell has only 1 s orbital, so the only possible value for ml is 0.

The spin quantum number (ms) describes the spin of the electron and can take 2 values: + 1/2 or - 1/2.

Considering these rules, the quantum numbers for these 4 electrons are:

n: 1, ℓ: 0, ml: 0, ms:+1/2

n: 1, ℓ: 0, ml: 0, ms:-1/2

n: 2, ℓ: 0, ml: 0, ms:+1/2

n: 2, ℓ: 0, ml: 0, ms:-1/2