Question

solubility always increases as temperature increases.
at 40°c, kcl has the highest solubility of the salts in the table.
the rate of change in the solubility of kno₃ changes as temperature increases.
the solubility of nacl does not increase with increasing temperatures above 80°c.

Explanation:

1. Analyze the solubility - temperature graph for each salt. For the first statement, the solubility of \(Ce_2(SO_4)_3\) decreases with increasing temperature, so it is false.
2. At \(40^{\circ}C\), \(Pb(NO_3)_2\) has a higher solubility than \(KCl\), so the second statement is false.
3. The slope of the \(KNO_3\) solubility - temperature curve changes, indicating that the rate of change of its solubility with temperature changes, so the third statement is true.
4. The solubility of \(NaCl\) continues to increase (albeit slightly) above \(80^{\circ}C\), so the fourth statement is false.

Answer:

The rate of change in the solubility of \(KNO_3\) changes as temperature increases.