The solubility of the gas in a liquid :
(A) Increases with increase in pressure
(B) Decreases with increase in pressure
(C) Increases with increase in temperature
(D) Decreases with increase in temperature
Choose the correct answer from the options given below:

(A), (D) only

The correct answer is Option (2) → (A), (D) only

Let us explore the solubility of gases in liquids in detail, focusing on how pressure and temperature affect this property.

Solubility of Gases in Liquids
The solubility of a gas in a liquid refers to the maximum amount of that gas that can dissolve in the liquid under specific conditions. This process involves the interaction between gas molecules and the liquid's solvent molecules.

Effect of Pressure on Gas Solubility

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 in equilibrium with the liquid. Mathematically, it can be expressed as:

\(C = k_H \cdot P\)

where:

\(C\) is the concentration of the dissolved gas,

\(k_H\) is the Henry's Law constant (depends on the gas and the solvent at a specific temperature),

\(P\) is the partial pressure of the gas.

When the pressure of a gas above a liquid is increased, more gas molecules are "pushed" into the liquid. This results in an increase in the number of gas molecules that can be accommodated in the solvent, hence increasing solubility.

Effect of Temperature on Gas Solubility

General Trend:

For most gases, the solubility in liquids decreases as the temperature increases. This is contrary to the behavior of most solids, where solubility generally increases with temperature.

At higher temperatures, the kinetic energy of gas molecules increases. As a result, the gas molecules tend to escape from the liquid into the gas phase more readily, reducing the amount of gas that can remain dissolved in the liquid.
  - Additionally, increased temperature typically results in greater vapor pressure for the gas, leading to a higher tendency for gas molecules to leave the solution.

Increasing Pressure (A):

More gas molecules dissolve as the pressure increases, enhancing solubility due to the increased likelihood of gas molecules interacting with the solvent.

Increasing Temperature (C):

This is generally incorrect for gases, as solubility decreases with an increase in temperature.

Decreasing Temperature (D):

As temperature increases, solubility decreases, as described earlier. This is because gas molecules gain energy and escape the liquid more easily.

Real-World Applications

Carbonated Beverages: In soda, carbon dioxide (CO₂) is dissolved under high pressure. When you open the can, the pressure drops, and CO₂ escapes, forming bubbles.

Aquatic Life: Fish and other aquatic organisms rely on dissolved oxygen in water. As water temperature rises (especially in summer), the solubility of oxygen decreases, which can lead to lower oxygen levels in the water, affecting aquatic life.

Conclusion
In summary, the solubility of gases in liquids is significantly influenced by pressure and temperature. Increased pressure enhances gas solubility, while increased temperature typically decreases it. Understanding these relationships is crucial in fields such as chemistry, environmental science, and various industrial processes.