Question 4
At 25 °C the solubility of magnesium chloride in water is 53.0 g and that of potassium sulphate is 12.0 g. Which conclusion does not follow?
The right answer is the one marked above.
Magnesium chloride dissolves faster than potassium sulphate. Solubility says how much dissolves, not how quickly. Nothing in those two figures is about time at all.
The other three are exactly what the pair of figures establishes — and it is only because the solvent and the temperature are the same for both that they can be compared.