Final answer:
Compound X has the lowest molar solubility in water.
Step-by-step explanation:
The compound with the lowest molar solubility in water is Compound X.
To determine the solubility of the compounds, we need to assess the relative magnitude of the enthalpy change for each step in the process. Then, we can use a solubility table to predict the solubility of each compound in water.
Since the question does not provide information about the compounds, such as their formulas or chemical structures, we cannot provide specific values for their solubility. However, we can use general trends to make an educated guess. For example, ionic compounds with larger ions or higher charges tend to be less soluble in water.