Answer: Option (B) is the correct answer.
Step-by-step explanation:
In the given graph, rate of increase in solubility means that as the temperature is increasing there is also increase in solubility.
Since, we have to find the constant rate of increase in solubility which means that for any particular temperature interval there will be same amount of increase in solubility.
That is, for potassium iodide the readings are (0, 130), (30, 180), (60, 230) etc. So, the difference in solubility will be (180 -130) = 50 and (230 -180) = 50.
This shows that rate of solubility constantly increases with a difference of 50 each time.
Thus, we can conclude that potassium Iodide is the compound which demonstrated a constant rate of increase of solubility as the temperature was increased from 0°C to 60°C.