In the experimental setup given below, it is observed that on passing the gas produced in the reaction in the solution 'X' the solution 'X' first turns milky and then colourless. The option that justifies the above stated observation is that 'X' is aqueous calcium hydroxide and

Quick Oral Answer

The correct option is (b) because the reaction between carbon dioxide and calcium hydroxide first forms calcium carbonate, which is insoluble in water and turns the solution milky. Then, on passing excess carbon dioxide, calcium hydrogen carbonate is formed, which is soluble in water and turns the solution colorless.