It is said that aqua regia can dissolve or corrode highly unreactive
Metals like gold and platinum.
Then how it is stored? In which container?
You should never store aqua regia. It is highly unstable and potentially explosive. It will oxidize quickly to form toxic nitrosyl chloride, nitrogen dioxide and chlorine gases. This will pressurize a closed container causing an explosion.
Prepare a fresh solution only when needed, in a glass container. While mixing, add conc.Nitric acid slowly and cautiously to the conc.Hydrochloric acid. Handle the apparatus carefully and always wear a labcoat, safety glasses, faceshield, fumehood and appropriate gloves. After use, leave the aqua regia solution in an open container until cool. Keep away from organic and reactive components.
When the solution has cooled down, it must be neutralized with sodium bicarbonate and disposed via the drain, followed by excess amount of water.