A student was to identify three unknown solutions with the knowledge they were nitrate salts of lead(II), mercury(II), and silver. To a small portion of each sample, five drops of sodium chloride solution was added. Two solutions formed a white precipitate while the other remained clear. To a second portion of each, sample five drops of sodium iodide solution was added. Two solutions formed yellow precipitates, while the third produced a red precipitate. To a third portion of each unknown solution, five drops of acetic acid solution was added. All three produced clear solutions. However, upon cooling one of the reaction pairs began to precipitate. Could these results be used in identifying the unknown solutions? Explain how the student used these results in identifying the solutions; you will need to identify the characteristics of the iodide precipitates to properly answer this question. Cite the source(s) used in obtaining this information.