Passing excess carbon dioxide through lime water initially produces a white precipitate of insoluble calcium carbonate, causing milkiness. On continued bubbling, carbon dioxide dissolves in water to form carbonic acid which reacts with calcium carbonate to yield calcium bicarbonate. Calcium bicarbonate is soluble in water, so the precipitate dissolves and the milky appearance disappears. Therefore insoluble calcium carbonate converts to a soluble bicarbonate on excess CO₂, explaining the clearing of lime water in this common laboratory demonstration today. Correct option – B.