Solid $Li X_{2} CO X_{3}$ is shaken with water and $CO X_{2}$ is passed until a clear solution forms. The clear solution is then boiled and a white precipitate X separates. The species dissolved in the clear solution and the precipitate X are:

Answer: A

Sparingly soluble carbonate dissolves with

CO X_{2}

Li X_{2} CO X_{3} + CO X_{2} + H X_{2} O 2 LiHCO X_{3}

, so the clear solution holds

LiHCO X_{3}

(stable only in solution). Boiling reverses it to

Li X_{2} CO X_{3}

with

CO X_{2}

loss. Li2O would not form in boiling water, since the oxide would immediately react with water to give LiOH.