Question

Is mixture of aqua regia is done by weight or volume ?

Answer 1

Keep in mind, concentrated HCl is about 35%, while concentrated HNO3 is about 65%, so the volume ratio is usually 4 parts concentrated hydrochloric acid to 1 part concentrated nitric acid. A typical total final volume for most applications is only 10 milliliters. It's unusual to mix up a large volume of aqua regia.

Answer 2

the mixture of aqua regia is done by volume