Question

Which of the following statement(s) is/are incorrect regarding nitric acid?

• A. Nitric acid is colourless liquid, but on exposure to light it turns yellow
• B. The enhanced power of aqua regia to dissolve metals is due to oxidising power of $HNO_3$ coupled with ability of $CI^-$ to form complexes with metal ions
• C. Birkeland-Eyde process is first synthetic method for preparation of $HNO_3$
• D. The Ostwald's process gives a $HNO_3$ solution of concentration 68% by weight

Answer 1

Answer: (C)

C

Answer 2

Statement A is correct because nitric acid decomposes to nitrogen dioxide (a reddish-brown gas) on exposure to light, which dissolves in the acid and imparts a yellow color.

Statement B is correct because aqua regia's effectiveness stems from nitric acid's oxidizing power and the ability of chloride ions from hydrochloric acid to form stable complex ions with metal ions, which drives the dissolution equilibrium forward.

Statement D is correct because the Ostwald process typically produces nitric acid at about 68% by weight, which corresponds to the azeotropic composition of nitric acid and water.

Statement C is incorrect because while the Birkeland-Eyde process was an early industrial method for synthesizing nitric acid from atmospheric nitrogen, Henry Cavendish's experiments in 1784 demonstrated the synthesis of nitric acid from air using electric sparks, predating the Birkeland-Eyde process by over a century.