The graph shows how the solubility of various chemicals varies with

Official Explanation

By following the gridline at 60°C, the visible line indicating the solubility of \(NaNO_{3}\) is highest on the graph. However, the line for KI extends above the scale shown on the graph. So, given the assumption that the curves continue in the same general shape beyond the plotted area, the information given indicates that KI is the most soluble at 60°C.

The correct answer is KI.

The vertical distance between the solubility curves for KClO3 and NH4Cl decreases as the temperature increases, thus the difference in solubility between KClO3 and NH4Cl decreases as the temperature increases. Assuming that the curves continue in the same general shape beyond the plotted area, the vertical distance between them will eventually be zero, thereby indicating that there is a temperature at which the two chemicals are equally soluble. By contrast, the solubility curves for KCl and NaCl have increasingly greater vertical distances from that of NH4Cl as the temperature increases. Thus the differences in the solubilities of either KCl or NaCl as compared to that of NH4Cl would continue to increase as the temperature increases.

The correct answer is KClO3.