What would you observe when:
$(a)$ a saturated solution of potassium chloride prepared at $60^{\circ} C$ is allowed to cool at room temperature?
$(b)$ an aqueous sugar solution is heated to dryness?
$(c)$ a mixture of iron filings and sulphur powder is heated strongly?

(N/A) Solid potassium chloride will separate out as crystals because the solubility of the salt decreases with a decrease in temperature.
$(b)$ Initially,the water will evaporate,leaving behind sugar crystals. Upon further heating,the sugar will get charred (decomposed into carbon).
$(c)$ $A$ chemical reaction occurs,and iron sulphide $(FeS)$ will be formed,which is a new substance with different properties.