Assertion–Reason (Chemistry of noble gases) Assertion (A): Helium, Argon, and Neon exist as gases at room temperature. Reason (R): The atoms of Helium, Argon, and Neon are chemically extremely inactive (noble/inert gases).

Introduction:
Assertion–Reason questions test whether you can judge the validity of two statements and also assess causation. Here, we analyze why Helium, Neon, and Argon are gaseous at room temperature and whether their chemical inertness fully explains this physical state.

Given Data / Assumptions:

• Noble gases considered: He, Ne, Ar.
• Room temperature context (around 25 °C, 1 atm).
• Atomic (monoatomic) gases with closed-shell electron configurations.

Concept / Approach:

Noble gases are chemically inert due to filled valence shells that make formation of stable chemical bonds unlikely under ordinary conditions. Their gaseous state at room temperature is primarily a matter of weak intermolecular forces (London dispersion) and very low polarizability, which keep boiling and melting points extremely low. Chemical inactivity and weak intermolecular attractions share an underlying electronic cause (closed shells), but inertness itself is not the immediate explanation for the gaseous state; intermolecular force magnitude is.

Step-by-Step Solution:

Verification / Alternative check:

Boiling points: He (−269 °C), Ne (−246 °C), Ar (−186 °C) are far below room temperature, consistent with weak intermolecular forces, independent of the notion of reactivity in chemical reactions.

Why Other Options Are Wrong:

Option A: claims correct explanation, which is inaccurate. Option C/D misjudge truth values. Option E is incorrect since both statements are true.

Common Pitfalls:

Equating chemical reactivity with physical state; ignoring the role of intermolecular forces and polarizability in determining boiling/melting points.

Final Answer:

Both A and R are true but R is not correct explanation of A