Explain why:

(i) Common salt becomes sticky during the rainy season

(ii) Blue vitriol changes to white upon heating

(iii) If bottle full of concentrated sulphuric acid is left open in the atmosphere by accident, the acid starts flowing out of the bottle of its own.

(i) Common salt contains the impurity of magnesium chloride (MgCl₂) which is of deliquescent nature. When exposed to atmosphere, it becomes moist. Therefore, common salt becomes sticky during the rainy reason.

(ii) Blue vitriol (CuSO₄.5H₂O) upon heating changes to anhydrous copper sulphate (CuSO₄) which is
white in colour.

(iii) Concentrated sulphuric acid is highly hygroscopic. It absorbs moisture from air and gets diluted. Since the volume increases, the acid starts flowing out of the bottle.