One day Reeta went to a jeweller 's shop with her mother. Her mother gave old gold jewellery to the goldsmith to polish . Next day when they brought the jewellery back, they found that there was a slight loss in its weight. Can you suggest reason for the loss in weight?

Explanation

In polishing, the jeweller put the gold jewellery in a liquid called aqua regia 3:1 (a mixture of hydrochloric acid and nitric acid) on getting the environment of aqua regia the outer layer of gold dissolves and the inner shiny layer appears. The dissolving of the layer causes a reduction in the weight of the jewelley.