CO is readily absorbed by ammoniacal cuprous chloride solution but `CO_2` is not. Explain.

Explanation

CO has a lone pair of electrons on C-atom. Thus, it acts as a Lewis base and forms a soluble complex with ammoniacal CuCl solution.
`CuCl + NH_3 + Coto [Cu(CO)NH_3]^(+)Cl^(-)` (Soluble)
`CO_2`, on the other hand, does not possess lone pair of electrons on C-atom. Hence, it does not act as a Lewis base. Thus, it does not dissolve in ammoniacal CuCl solution.