Which of the following substances would become more soluble in water as the pressure above the solution increases?

• A. AgCl (silver chloride)
• B. NaCl (sodium chloride)
• C. C_6H_{12}O_6 (glucose)
• D. CO_2 (carbon dioxide gas)

Answer: (D)

Verified step by step guidance

1. Understand the nature of solubility and how it depends on pressure. Solubility of gases in liquids generally increases with increasing pressure, according to Henry's Law.
2. Recall Henry's Law, which states that the solubility of a gas in a liquid is directly proportional to the partial pressure of that gas above the liquid. Mathematically, this is expressed as \(C = k_{H} \times P\), where \(C\) is the concentration of the dissolved gas, \(k_{H}\) is Henry's law constant, and \(P\) is the partial pressure of the gas.
3. Analyze the substances given: AgCl, NaCl, and glucose are solids or molecular compounds that dissolve based on their ionic or molecular interactions with water, and their solubility is generally not significantly affected by pressure changes.
4. Recognize that CO\(_2\) is a gas, and its solubility in water will increase as the pressure of CO\(_2\) gas above the solution increases, following Henry's Law.
5. Conclude that among the substances listed, only CO\(_2\) will become more soluble in water as the pressure above the solution increases.