Which of the following element does not belong to the family of elements indicated

Options

A. Rubidium (Rb,Z=37) : Alkali metals
B. Barrium (Ba,Z=56): Alkaline earth metals
C. Iridium (Ir,Z=77) : Noble gases
D. Argon (Ar,Z=18): Noble gas

Explanation

To determine which element does not belong to the indicated family of elements, we will analyze the given elements based on their atomic numbers and their respective groups in the periodic table.

### Step-by-Step Solution:

1. **Identify the Elements and Their Atomic Numbers**:
- Rubidium (Rb) - Atomic number 37
- Barium (Ba) - Atomic number 56
- Iridium (Ir) - Atomic number 77
- Argon (Ar) - Atomic number 18

2. **Classify the Elements**:
- **Rubidium (Rb)**: This is an alkali metal, which belongs to Group 1 of the periodic table.
- **Barium (Ba)**: This is an alkaline earth metal, which belongs to Group 2 of the periodic table.
- **Iridium (Ir)**: This is a transition metal, which belongs to the D-block of the periodic table.
- **Argon (Ar)**: This is a noble gas, which belongs to Group 18 of the periodic table.

3. **Determine the Family of Elements**:
- The question asks which element does not belong to the family indicated.
- Alkali metals (Group 1) and alkaline earth metals (Group 2) are both S-block elements.
- Transition metals (D-block) and noble gases (Group 18) are distinctly different families.

4. **Identify the Odd One Out**:
- Rubidium and Barium are both S-block elements.
- Iridium is a D-block element.
- Argon is a noble gas and does not belong to the S-block elements.

5. **Conclusion**:
- The element that does not belong to the family of elements indicated (S-block elements) is **Iridium (Ir)**.

### Final Answer:
**Iridium (Ir)** does not belong to the family of elements indicated.