The group VIII elements are the inert gases because they

Analysis

The question asks for the reason why Group VIII elements (also known as Group 0 or Noble Gases) are chemically inert, meaning they are generally unreactive under standard conditions.

Concept Explanation

The chemical reactivity of an element is primarily determined by its electron configuration, specifically the electrons in its outermost shell (the valence shell).

• The Octet Rule: Atoms tend to gain, lose, or share electrons to achieve a stable electron configuration, which usually means having a full outer shell (typically 8 electrons, or 2 for Helium).
• Noble Gases: Elements in Group VIII (Helium, Neon, Argon, Krypton, Xenon, and Radon) already possess a stable, "closed-shell" configuration. Their valence shells are completely filled with electrons. Because they are already stable, they have no "need" to gain, lose, or share electrons with other atoms, which is why they do not readily form chemical bonds.

Step-by-Step Solution

1. Examine Option A: While some noble gases can form compounds under extreme conditions (like Xenon fluorides), they do not have "lone pairs" in the way that makes them reactive in the context of standard bonding; their stability comes from the fullness of the shell.
2. Examine Option B: This is the definition of their stability. Helium has a full $1s^2$ shell, and the others have a full $ns^2 np^6$ configuration. This complete filling creates a high ionization energy and low electron affinity, making them inert.
3. Examine Option C: This is factually incorrect. Noble gases are gases at room temperature, not solids.
4. Examine Option D: This is factually incorrect. Noble gases are monatomic (they exist as single atoms), not polyatomic.

Conclusion

The stability and inert nature of Group VIII elements are due to their completely filled valence shells, which provide a low-energy, stable state.

Exam Tip: Whenever you see a question about "Noble Gases" or "Inert Gases," always look for keywords like "stable," "full valence shell," "octet configuration," or "monatomic." If you see options mentioning "solids" or "polyatomic," you can immediately eliminate them!