Correct Option
The correct option is Pressure.
Explanation
Henry's Law describes the behavior of gas solubility in liquids. It states that at a constant temperature, the solubility of a gas in a liquid is directly proportional to the partial pressure of the gas present above the surface of the liquid or solution. Mathematically, this is expressed as \( p = K_H \chi \), where \( p \) is the partial pressure of the gas, \( K_H \) is Henry's Law constant, and \( \chi \) is the mole fraction of the gas in the solution.
Detailed Analysis
- Pressure is Correct: As per Henry's Law, increasing the pressure on the gas above the liquid surface forces more gas molecules into the solution to relieve the applied stress. Consequently, the solubility of the gas increases.
- Temperature is Incorrect: The dissolution of a gas in a liquid is generally an exothermic process. According to Le Chatelier's principle, increasing the temperature shifts the equilibrium towards the backward direction, causing the gas to escape. Thus, solubility decreases with an increase in temperature.
- Light intensity is Incorrect: Light intensity is not a thermodynamic variable that directly governs the physical solubility of gases in liquids.
- Stirring speed is Incorrect: Stirring speed influences the rate (kinetics) at which equilibrium is reached but does not alter the equilibrium solubility itself. The maximum amount of gas dissolved depends on pressure and temperature, not on agitation.
Key Takeaway: The solubility of a gas in a liquid is directly determined by the pressure of the gas (Henry's Law) and is inversely related to the temperature of the system.