**Solubility of Noble Gases in Water**

Noble gases, also known as Group 18 elements, are known for their low reactivity and stability due to their full outer electron shells. These elements include helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn). Among these noble gases, radon (Rn) is the most soluble in water.

**Factors Affecting Solubility in Water**

The solubility of a gas in water depends on several factors, including temperature, pressure, and the nature of the gas molecules.

1. **Temperature**: Generally, the solubility of gases decreases with increasing temperature. This is because higher temperatures provide more energy to the gas molecules, enabling them to escape from the liquid phase and enter the gas phase more easily. Conversely, lower temperatures reduce the energy of the gas molecules, making them more likely to dissolve in the liquid phase.

2. **Pressure**: The solubility of gases in water also increases with increasing pressure. This is because higher pressures force more gas molecules into the liquid phase, increasing the overall solubility. Conversely, lower pressures result in fewer gas molecules dissolving in water.

3. **Nature of Gas Molecules**: The nature of the gas molecules themselves also plays a role in their solubility in water. Polar gases, which have unequal distribution of charge (such as carbon dioxide), tend to be more soluble in water due to the water's polar nature. Nonpolar gases, on the other hand, such as noble gases, have no charge distribution and are less soluble in water.

**Solubility of Noble Gases in Water**

Among the noble gases, radon (Rn) is the most soluble in water. This is due to several factors:

1. **Atomic Size**: Radon has the largest atomic size among the noble gases. The larger the atomic size, the greater the dispersion forces between the gas molecules and the water molecules. These dispersion forces, also known as London forces, are weak attractive forces that arise due to temporary fluctuations in electron distribution. The larger the atomic size, the greater the number of electrons available for dispersion forces, leading to increased solubility.

2. **Polarizability**: Radon, with its larger atomic size, also exhibits greater polarizability. Polarizability refers to the ease with which the electron cloud of an atom or molecule can be distorted by an external electric field. The higher the polarizability, the stronger the dispersion forces. Radon's larger atomic size allows for greater electron cloud distortion, leading to stronger dispersion forces and increased solubility in water.

Overall, due to its larger atomic size and higher polarizability, radon is the most soluble noble gas in water.