Question

One day Reeta went to a jeweller’s shop with her mother. Her mother gave an 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

When gold jewellery needs to be polished. ​

• It is dipped in an acidic solution aqua regia, a mixture of nitric acid and hydrochloric acid.​
• On dissolving gold in aqua regia, its outer layer gets dissolved and inner shiny layer comes out.​

Thus, the weight of the gold jewellery is reduced due to the dissolution of the outer layer.