Question

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 a reason for the loss in weight?

Answer 1

To polish a gold ornament, the goldsmiths usually dip it in a liquid called aqua regia. Aqua regia is a mixture of nitric acid and hydrochloric acid.
When gold is dipped in this liquid, the outer layer of gold dissolves in it and the inner shiny layer gets exposed.
Because of the dissolution of the upper layer of jewellery, its weight gets slightly reduced.