15. What would you observe when :(i) A saturated solution of potassium chloride prepared at 60°C is allowed to cool at room temperature?(ii) An aqueous sugar solution is heated to dryness?(iii) A mixture of iron filings and sulphur powder is heated strongly?

(i) The given solution is a saturated solution of potassium chloride prepared at 60°C which is above the room temperature (20°C). Therefore, when it is allowed to cool at room temperature, some of the potassium chloride will settle down at the bottom, because saturation decreases with decrease in temperature and vice versa. (ii) When an aqueous solution of sugar is heated to dryness, the water will evaporate and the sugar will be left behind in the container. But, the sugar left in the container may be burnt because of more heating. (iii) When a mixture of iron filings and sulphur powder is heated strongly, compound FeS (Ferrous Sulphide) is formed.