Final answer:
A 90g NaNO₃ solution in 100g of water at 30 degrees C is unsaturated.
Step-by-step explanation:
A saturated solution is one that contains the maximum amount of solute that is capable of dissolving in a given amount of solvent. In this case, 90g of NaNO₃ is dissolved in 100g of water at 30 degrees C. To determine the type of solution, we compare the given amount of solute to the maximum solubility of NaNO₃ in water at that temperature. If the given amount of solute is equal to or less than the maximum solubility, the solution is saturated. If it is greater, the solution is unsaturated. According to the provided information, the given amount of solute is 90g, which is greater than the maximum solubility of NaNO₃ at 30 degrees C. Therefore, the solution is unsaturated.
Therefore, the correct answer is B) Unsaturated.