**Correct Option: B. The pressure of the gas above the liquid** ### Detailed Explanation: To understand why the pressure of the gas above the liquid primarily affects the solubility of a gas in a liquid, we can refer to Henry's Law. Henry's Law states that at a constant temperature, the amount of gas that dissolves in a liquid is directly proportional to the partial pressure of that gas above the liquid. The mathematical representation of Henry's Law is: \[ C = k_H \cdot P \] Where: - \( C \) is the concentration of the dissolved gas in the liquid (usually in mol/L). - \( k_H \) is Henry's Law constant (which varies for different gases and solvents). - \( P \) is the partial pressure of the gas above the liquid. **Step-by-Step Explanation:** 1. **Understanding Henry's Law**: According to Henry's Law, if you increase the pressure of the gas above the liquid, more gas molecules are forced into the liquid, increasing the solubility. Conversely, if the pressure decreases, the solubility of the gas decreases as well. 2. **Real-World Application**: This principle is observed in carbonated beverages. When the can or bottle is sealed, the pressure of carbon dioxide (CO₂) gas is high, allowing a significant amount of CO₂ to dissolve in the liquid. Once opened, the pressure drops, and the gas escapes, leading to the fizzing effect as the gas comes out of solution. 3. **Temperature Consideration**: While temperature does affect solubility, it is more significant for solids and liquids than for gases. Generally, as temperature increases, the solubility of gases decreases because the increased kinetic energy allows gas molecules to escape from the liquid more easily. However, the primary factor affecting gas solubility at a given temperature is pressure. ### Why Other Options Are Incorrect: - **A. The surface area of the solute**: This option is more relevant to solid solutes dissolving in liquids. For gases, the surface area is not a significant factor because gas molecules are already in the gaseous state and can easily diffuse into the liquid. The interaction between gas molecules and the liquid is primarily influenced by pressure. - **C. The temperature of the liquid**: While temperature does affect the solubility of gases, it is not the primary factor at a given temperature. As mentioned earlier, increasing temperature generally decreases gas solubility, but the effect of pressure is more direct and significant in determining how much gas can dissolve. - **D. The presence of other solutes in the solution**: This can affect the solubility of gases, but it is not the primary factor. The presence of other solutes can lead to changes in the solvent properties (like colligative properties), but the direct relationship between gas pressure and solubility is much stronger. ### Summary: - The solubility of a gas in a liquid is primarily affected by the pressure of the gas above the liquid, as described by Henry's Law. - Increasing the pressure increases the amount of gas that can dissolve in the liquid. - Temperature affects gas solubility but is not the primary factor at a constant temperature. - The surface area of the solute and the presence of other solutes have less impact on gas solubility compared to pressure. This understanding is crucial for applications in chemistry, environmental science, and various industrial processes involving gases and liquids.