The boiling points of noble gases are illustrative of the operation of forces of the type :

Options

A. ion-dipole
B. dipole-induced dipoles
C. ion-induced dipole
D. London dipersion forces

Answer

To solve the question regarding the boiling points of noble gases and the type of forces that operate, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Nature of Noble Gases**:
- Noble gases (Helium, Neon, Argon, Krypton, Xenon, and Radon) are known for their low reactivity due to their complete valence electron shells.

2. **Identify the Boiling Points**:
- Noble gases have low boiling points compared to other elements. For example, Helium has the lowest boiling point, while Radon has the highest among them.

3. **Determine the Type of Intermolecular Forces**:
- The boiling points of substances are influenced by the type of intermolecular forces present. For noble gases, the relevant forces are:
- Ion-dipole forces
- Dipole-induced dipole forces
- Ion-induced dipole forces
- London dispersion forces

4. **Focus on London Dispersion Forces**:
- Among the listed forces, noble gases primarily exhibit London dispersion forces, which are weak intermolecular forces arising from temporary dipoles created when electron clouds fluctuate.

5. **Relate Size to Boiling Points**:
- The strength of London dispersion forces increases with the size of the atom. As you move down the group of noble gases, the atomic size increases, leading to stronger London dispersion forces and thus higher boiling points.

6. **Conclude the Answer**:
- Therefore, the boiling points of noble gases are illustrative of the operation of London dispersion forces. Hence, the correct answer is that the boiling points of noble gases are indicative of London dispersion forces.

### Final Answer:
The boiling points of noble gases are illustrative of the operation of forces of the type: **London dispersion forces**.

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