Which one of the following reactions will give NO (nitric oxide) gas as one of the products?
3Cu + 8HNO₃ (dilute)→
Cu + 4HNO₃ (conc.)→
4Zn + 10HNO₃ (dilute)→
Zn + 4HNO₃ (conc.)→
Answer is Wrong!
Answer is Right!
This question was previously asked in
UPSC NDA-2 – 2018
– The specific nitrogen oxide produced depends on the concentration of HNO₃ and the reactivity of the metal. Dilute HNO₃ reacts with moderately reactive metals like copper to produce NO. Concentrated HNO₃ reacts with most metals (except very unreactive ones) to produce nitrogen dioxide (NO₂).
– Reaction with very dilute HNO₃ and highly reactive metals (like Zn): 4Zn + 10HNO₃ (very dilute) → 4Zn(NO₃)₂ + N₂O + 5H₂O (produces nitrous oxide, N₂O) or even NH₄NO₃. The reaction given in option C with dilute HNO3 producing N2O is also correct for zinc.