The solubility of most ionic solids increases with increasing temperature. However, there are many exceptions to this rule. Which of the following salts shows a decrease in the solubility as the temperature goes up?

Options

A. `KNO_(3)`
B. `CuSO_(4)`
C. `NaCl`
D. `Ce_(2)(SeO)_(3)`

Answer

4

Explanation

First three salts show the usual behaviour, their solubilities increase with rising temperature. Potassium nitrate `(KNO_(3))` changes solubility dramatically from `14 g//100g H_(2)O` at `0^(@)C` to `245 g//100 g H_(2)O` at `100^(@)C`. Copper sulphate `(CuSO_(4))` shows a moderate increase in solubility over this temperature interval. Sodium chloride `(NaCl)` increases only slightly in solubility with temperature.
Cerium selenate `[Ce_(2)(SeO_(4))_(3)]` is very soluble at `0^(@)C` but much less soluble at `100^(@)C`.