Question:
Aqua regia is used for dissolving noble metals (Au, Pt, etc). The gas evolved in this process is :
Correct Option: , 3
Solution:
$\mathrm{Au}+\mathrm{HNO}_{3}+4 \mathrm{HCl} \rightarrow \mathrm{HAuCl}_{4}+\mathrm{NO}+2 \mathrm{H}_{2} \mathrm{O}$