A woman gave old and dull gold bangles to a goldsmith for polishing to restore their glitter. The goldsmith dipped the gold bangles in a particlular solution. The bangles sparkled like new but their weight was reduced drastically. Can you guess the solution used by the dishonest gold smith.?

Explanation

The dishonest goldsmith dipped the gold bangles in aqua-regia solution (which contains 1 part of concentrated nitric acid and 3 parts of concentrated hydrochloric acid, by volume). Aqua-regia dissolved a considerable amount of gold from gold bangles and hence reduced their weight drastically. The dishonest goldsmith can recover theh dissolved gold from aqua-regia by a suitable treatment.