Which of the following is not a noble gas ?

Options

A. helium
B. xenon
C. radium
D. radon

Answer

To determine which of the following elements is not a noble gas, we can follow these steps:

### Step 1: Understand the Noble Gases
Noble gases are a group of elements found in Group 18 of the modern periodic table. They are known for their lack of reactivity due to having a full valence shell of electrons. The noble gases include:
- Helium (He)
- Neon (Ne)
- Argon (Ar)
- Krypton (Kr)
- Xenon (Xe)
- Radon (Rn)

### Step 2: Identify the Elements Given
If we are provided with a list of elements, we need to identify which ones are noble gases and which one is not. For example, if the options are:
1. Helium (He)
2. Neon (Ne)
3. Radium (Ra)
4. Argon (Ar)

### Step 3: Analyze Each Option
- **Helium (He)**: This is a noble gas.
- **Neon (Ne)**: This is also a noble gas.
- **Radium (Ra)**: This is NOT a noble gas; it is an alkaline earth metal found in Group 2.
- **Argon (Ar)**: This is a noble gas.

### Step 4: Conclusion
From the analysis, we can conclude that Radium (Ra) is the element that is not a noble gas.

### Final Answer
Radium (Ra) is not a noble gas.

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