Which of the following best explains why noble gases are so unreactive?

• A. They have unstable nuclei that prevent chemical bonding.
• B. They easily lose electrons to form positive ions.
• C. They have very high electronegativity values.
• D. They have completely filled valence electron shells.

Answer: (D)

Verified step by step guidance

1. Understand that chemical reactivity is largely determined by the electron configuration of an element, especially the electrons in the outermost shell, called valence electrons.
2. Recall that noble gases are located in Group 18 of the periodic table and are known for their lack of chemical reactivity under normal conditions.
3. Recognize that noble gases have completely filled valence electron shells, meaning their outermost energy level has the maximum number of electrons possible, making them very stable.
4. Know that because their valence shells are full, noble gases have little tendency to gain, lose, or share electrons, which is why they do not easily form chemical bonds.
5. Conclude that the best explanation for the unreactivity of noble gases is their completely filled valence electron shells, rather than factors like nuclear stability, ion formation, or electronegativity.