Which of the following gas is released when copper reacts with dil. nitric acid?
NO
Copper reacts with dil.HNO3 and liberates nitric oxide gas.
3Cu+8HNO3(dil)→3Cu(NO3)2+2NO↑+4H2O
Copper reacts with conc. HNO3 and conc. H2SO4 and liberates nitrogen dioxide and sulphur dioxide respectively.
Cu+4HNO3(conc.)→Cu(NO3)2+2NO2↑+2H2O
Cu+2H2SO4(conc.)→CuSO4+SO2↑+2H2O