# Question #db5fb

Using “Normal” temperature (20’C) and pressure (1 atm) $C {O}_{2}$ is a gas, ${H}_{2} O$ can be either liquid or gas, MgO, NaCl, $A l C {l}_{3} , K N {O}_{3} , P b {I}_{2} , C u C {O}_{3}$ and Cu are all solids. All of them except elemental copper can be put into an aqueous solution.
At elevated pressure $C {O}_{2}$ can become a liquid, and at very low temperature it becomes a solid, as does ${H}_{2} O$.