Solubility of gas decreases in a liquid by

Options

A. Increase of temperature
B. Cooling
C. Increasing pH
D. Decreasing pH

Answer

To solve the question regarding how the solubility of a gas decreases in a liquid, we will analyze the options provided one by one.

### Step-by-Step Solution:

1. **Understanding the Question**:
The question asks how the solubility of a gas in a liquid decreases. We need to evaluate the provided options:
- A) Increase of temperature
- B) Cooling
- C) Increasing pH
- D) Decreasing pH

2. **Analyzing Option A: Increase of Temperature**:
- When the temperature of a liquid increases, the kinetic energy of the gas molecules also increases.
- Higher kinetic energy means that gas molecules move faster and are more likely to escape from the liquid into the gas phase.
- This results in a decrease in the solubility of the gas in the liquid because the gas molecules are breaking free from the solvent's attraction.
- **Conclusion**: Increasing temperature decreases the solubility of gas in a liquid.

3. **Analyzing Option B: Cooling**:
- Cooling a liquid means decreasing its temperature.
- A decrease in temperature generally leads to a decrease in kinetic energy of gas molecules.
- With lower kinetic energy, gas molecules are less likely to escape the liquid, which means solubility would increase.
- **Conclusion**: Cooling increases the solubility of gas in a liquid.

4. **Analyzing Option C: Increasing pH**:
- The effect of pH on gas solubility can vary depending on the specific gas and the nature of the liquid.
- For some gases, increasing pH may lead to decreased solubility, while for others it may not have a significant effect.
- Due to this variability, we cannot definitively say that increasing pH decreases gas solubility.
- **Conclusion**: The effect of increasing pH on gas solubility is not predictable.

5. **Analyzing Option D: Decreasing pH**:
- Similar to increasing pH, the effect of decreasing pH on gas solubility can also vary depending on the gas and the solvent.
- Thus, we cannot conclude that decreasing pH will universally decrease gas solubility.
- **Conclusion**: The effect of decreasing pH on gas solubility is also not predictable.

6. **Final Conclusion**:
- Based on the analysis, the only option that consistently leads to a decrease in gas solubility in a liquid is **Option A: Increase of temperature**.

### Final Answer:
**The solubility of gas decreases in a liquid by increasing temperature (Option A).**