Question

“A” obtained by Ostwald’s method involving air oxidation of\( NH_3\), upon further air oxidation produces “B”. “B” on hydration forms an oxoacid of Nitrogen along with evolution of “A”. The oxoacid also produces “A” and gives positive brown ring test. 

• A. \(NO, NO_2\)
• B. \(N_2O_3, NO_2\)
• C. \(NO_2, N_2O_4\)
• D. \(NO_2, N_2O_5\)

Hint:

For questions involving industrial processes:
• Understand key steps in the process (e.g., oxidation, hydration, and product formation).
• Focus on intermediate and final products to identify properties and tests.

Answer 1

The Correct Option is A

To solve this question, let's analyze the process and identify “A”, “B”, and the oxoacid involved:

1. According to Ostwald's method, ammonia (NH_3) is initially oxidized in the presence of air to form nitric oxide (NO). This reaction is:
   4NH_3 + 5O_2 \rightarrow 4NO + 6H_2O
2. The product “A” therefore is NO.
3. The further oxidation of “A” (i.e., NO) in air results in nitrogen dioxide (NO_2), which is identified as “B”. This reaction is:
   2NO + O_2 \rightarrow 2NO_2
4. Next, it is mentioned that “B” upon hydration forms an oxoacid of nitrogen, with the evolution of “A”. When NO_2 is hydrated, it forms a mixture of nitrous acid (HNO_2) and nitric acid (HNO_3) along with the evolution of “NO”:
   2NO_2 + H_2O \rightarrow HNO_2 + HNO_3
5. The classically recognized oxoacid of nitrogen that also gives a positive brown ring test is nitrous acid (HNO_2).
6. Based on the above reactions and identification of the nitrogen compounds involved, the correct pair matching the given process is: “A = NO”, “B = NO_2”.

Therefore, the correct answer is: NO, NO_2.