Question

Which of the following does not produce NO2 gas with Conc HNO,?
(1) Cu
(2) 12
(4) Au
(3) Ag

Answer 1

Gold doesn't react with conc. Nitric acid.

Explanation:

• Gold and platinum are inert metals. They do not actively react with other elements.
• They are placed under hydrogen and comes under electrochemical series.
• They are found to be least reactive and are inert. So gold and platinum can't react with nitric acid.
• Gold and platinum react in aquaregia (a mixture of conc. hydrochloric acid and conc. nitric acid in 3:1 ratio). They release nascent chlorine by oxidizing conc. acid.
• This nascent chlorine reacts with gold and platinum and provide chlorides.
• The soluble chlorides can be used for recovery of metals.

therefore, Au, ( gold ) do not produce nitric oxide with concentrated nitric acid.