Question

what will you observe when gold is placed in aqua regia

Answer 1

gold will dissolve in aqua Regia due to the production of nascent chlorine
3HCL + HNO3 ---> NOCL+2H2O+ 2[CL]
Au+3[CL]----->AuCl3

Answer 2

Aqua regia is a mixture of concentrated hydrochloric acid and concentrated nitric acid in the ratio 3:1.
This mixture has the ability to dissolve gold and platinum.

Gold will dissolve in few minutes when it is placed in aqua regia. You must have heard that jewellers clean the gold ornaments using aqua regia. But they shouldn't as it reduces the weight of the ornament. Aqua regia eats the gold from the ornament.