Q611
Commercial nitric acid is coloured because it contains dissolved :
A.
Oxygen
B.
Nitrous oxide
C.
Nitrogen dioxide
AnswerD.
Coloured impurities
Answer: Option C
Solution
Answer: Option C
Solution:
Commercial nitric acid has a brown colour due to dissolved NO2. The procedure of bubbling dry air through warm commercial nitric acid, is to drive away the dissolved nitrogen dioxide so that the acid becomes colourless.