An importance of solubility is that it

Analysis

The question asks for the fundamental definition or significance of solubility in chemistry. To answer this, we must look at what solubility actually measures and how it differs from colligative properties.

Concept Explanation

Solubility is defined as the maximum amount of a solute that can dissolve in a specific amount of solvent at a given temperature to form a saturated solution. It is a physical property that tells us the "limit" of dissolution for a particular substance.

Let's look at the other options:

• Options B and D: Lowering vapour pressure and raising the boiling point are colligative properties. These properties depend on the number of solute particles in a solution, not the specific identity or the solubility limit of the solute.
• Option C: Knowing the chemical reaction of a gas with a liquid is related to chemical kinetics or chemical equilibrium, not the physical limit of solubility.

Step-by-Step Solution

1. Define Solubility: Solubility is the concentration of a saturated solution. It quantifies how much solute can be accommodated by a solvent before no more can be dissolved.
2. Evaluate Option A: This option directly describes the definition of solubility—the capacity of a solvent to hold a specific amount of solute.
3. Evaluate Options B & D: These describe the effect of adding a solute to a solvent (colligative properties), but they do not define the concept of solubility itself.
4. Evaluate Option C: This refers to chemical reactivity, which is distinct from the physical process of dissolving.

Therefore, the most accurate description of the importance/definition of solubility is the determination of the maximum amount of solute that can be dissolved.

Conclusion

It is the only statement that correctly identifies the primary function of solubility as a measurement of solute capacity.

Exam Tip

When you see questions about "solubility," look for keywords like "maximum amount," "saturated," or "limit." If the question mentions "boiling point elevation" or "vapour pressure lowering," remember those are colligative properties, not solubility!