10. Exercises X

Answer the following question:

  

 

For polishing, the gold jewellery is dipped into an basicneutralacidic buffer solution called aqua regia (a mixture of hydrochloric acid and nitrous acidchloric acidsulfuric acidnitric acid). On dipping the gold jewellery in the acid solution, the outer layer of gold dissolves and the shiny inner layer appears. This causes a slight loss in its weightslight gain of its weightslight gain of its dullslight loss in its dull.