For which of the following activities might you want to hire a chemist? a: testing a rock sample for gold content b: building a wood storage shed c: building a fence d: examining the structure of plant cells i'm pretty sure i know the answer but i'd like to make sure i'm right.

OPTION (A) : Testing a rock sample for gold content

Explanation:

For testing a rock sample of gold content you will need a Chemist. To test the material, the sample is rubbed on black stone which will leave a mark on the stone. This mark is tested by applying aqua fortis i.e nitric acid on the mark. If the mark gets dissolve then the material is not gold. If the mark sustain the it is further tested by applying aqua regia i.e nitric acid and hydrochloric acid which will prove the sample is of gold if it gets dissolve on using hydrochloric acid. The purity of the sample can be checked by differing the concentration of the aqua regia and comparing it with the gold material of the known purity.

in the analysis of systems that involve fluid flow, we frequently encounter the combination of properties u and pv.