**Question:** Which one of the following is NOT true concerning Radon?

A. Radon is a radioactive gas
B. Radon is a noble gas
C. Radon is a product of radioactive decay
D. Exposure to Radon causes lung cancer

**Correct Answer:** B. Radon is a noble gas

**Core Concept:**
Radon is a chemical element with the symbol Rn and atomic number 86. It is classified as a radioactive gas due to its unstable atomic structure, which leads to radioactive decay. Noble gases, on the other hand, are a group of stable, unreactive gases found in Group 18 of the periodic table.

**Why the Correct Answer is Right:**
Radon is a radioactive gas because it undergoes radioactive decay, emitting alpha particles as it transitions from one atomic energy level to another. This process results in the release of energy and changes in the atomic structure, making it different from the stable and unreactive noble gases.

**Why Each Wrong Option is Incorrect:**
A. Radon is indeed a radioactive gas (Option A) and a product of radioactive decay (Option C). Noble gases, however, are characterized by their stability and unreactivity, which distinguishes them from radon.

B. Radon is classified as a radioactive gas due to its radioactive properties, not its chemical nature. Noble gases, on the other hand, are a group of stable, unreactive gases found in Group 18 of the periodic table.

C. While radon is a product of radioactive decay, it is not a noble gas. Noble gases are a group of stable, unreactive gases found in Group 18 of the periodic table.

D. Exposure to radon gas is known to cause lung cancer, which is consistent with the radioactive properties of radon. Noble gases, however, are not associated with causing lung cancer or any other health issues due to their stable chemical nature.

**Clinical Pearls:**
1. Radon is a radioactive gas that poses health risks when inhaled, as it can cause lung cancer due to the alpha particles emitted during radioactive decay.
2. Noble gases, being stable and unreactive, do not pose health risks to humans and are essential components of the periodic table.

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**Why the Correct Answer is Right:**
Radon is a radioactive gas due to its unstable atomic structure, which leads to radioactive decay and the release of alpha particles. This radioactive property distinguishes radon from noble gases, which are a group of stable, unreactive gases found in Group 18 of the periodic table.

**Why Each Wrong Option is Incorrect:**
A. This option is incorrect because radon is a radioactive gas, not a noble gas. Noble gases are a group of stable, unreactive gases found in Group 18 of the periodic table.

B. This option is incorrect because radon is a radioactive gas, not a noble gas. Noble gases are a group of stable, unreactive gases found in Group 18 of the periodic table.

C. This