Select the correct statement below:

(a) phosphorous contains 10 core electrons and 5 valence electrons. its orbital diagram contains one half-filled 3p orbital and two filled 3p orbitals.
(b) aluminum contains 10 core electrons and 3 valence electrons. its orbital diagram contains three half-filled 3p orbitals.
(c) calcium contains 18 core electrons and 2 valence electrons. its orbital diagram contains two half-filled 4s orbitals and no filled 4p orbitals.
(d) sodium contains 10 core electrons and 1 valence electron. its orbital diagram contains one half-filled 3s orbital and three empty 3p orbitals.

The correct answer is Option D.

Explanation:

Valence electrons are defined as the electrons which are present in the outermost shell of the atom. Outermost shell has the highest value of 'n' that is principal quantum number.

For the given options:

Phosphorus is the 15th element of the periodic table having electronic configuration

Number of valence electrons = 2 + 3 = 5

The '3s' orbital is fully filled and all the three '3p' orbitals are half filled for the given element.

So, the given statement is not correct.

Aluminium is the 13th element of the periodic table having electronic configuration

Number of valence electrons = 2 + 1 = 3

The '3s' orbital is fully filled and one of all the three '3p' orbitals is half filled and rest are empty for the given element.

So, the given statement is not correct.

Calcium is the 20th element of the periodic table having electronic configuration

Number of valence electrons = 2

The '4s' orbital is fully filled and all the three '4p' orbitals are half filled for the given element. '4s' sub-shell has only one orbital.

So, the given statement is not correct.

Sodium is the 11th element of the periodic table having electronic configuration

Number of valence electrons = 1

The '3s' orbital is half filled and all the three '3p' orbitals are half filled for the given element.

So, the given statement is not correct.

Hence, the correct answer is Option D.