Which of the following salts has the highest molar solubility in water at room temperature?

• A. AgCl
• B. NaNO_3
• C. CaCO_3
• D. BaSO_4

Answer: (B)

Verified step by step guidance

1. Understand that molar solubility refers to the number of moles of a salt that can dissolve in a liter of water to form a saturated solution at a given temperature.
2. Recall that the solubility of ionic salts in water depends on their solubility product constant, \(K_{sp}\), which quantifies the extent to which the salt dissociates into its ions in solution.
3. Recognize that salts like NaNO\(_3\) are generally highly soluble because they dissociate completely into ions (Na\(^+\) and NO\(_3^-\)) and have very large \(K_{sp}\) values, effectively making their solubility limited only by the amount added.
4. Compare the \(K_{sp}\) values of the other salts (AgCl, CaCO\(_3\), BaSO\(_4\)), which are known to be sparingly soluble salts with much smaller \(K_{sp}\) values, indicating lower molar solubility.
5. Conclude that the salt with the highest molar solubility is the one with the largest \(K_{sp}\) or that is known to be highly soluble, which in this case is NaNO\(_3\).