question_answer 30)

A man went door to door posing as a goldsmith. He promised to bring back the glitter of old and dull gold ornaments. An unsuspecting lady gave a set of gold bangles to him  which he dipped in a particular solution. The bangles sparkled like new but their weight was reduced drastically. The lady got upset and after a futile argument, the man beat a hasty retreat. Can you. predict the nature of the solution used by the imposter ?                        

Answer:

The man had actually used the solution of aqua regia (mixture of conc.  and conc. in the ratio of 3: 1by volume which has dissolved gold forming soluble auric chloride  Since gold actually reacted, there was a loss in weight of the gold bangles. With the removal of the dull layer of gold from the surface, there was original shine on the bangles.