A nitrate is heated with copper turnings and conc. H2SO4: Cu + 2NO3^- + 4H+ -> Cu^2+ + 2NO2 + 2H2O. The number of moles of brown gas formed per mole of copper consumed is

JEE Main levelSingle correct optionDifficulty 2 of 3qa045

A nitrate is heated with copper turnings and conc. $H X_{2} SO X_{4}$ : $Cu + 2 NO X_{3} X^{-} + 4 H X^{+} Cu X^{2 +} + 2 NO X_{2} + 2 H X_{2} O$ . The number of moles of brown gas formed per mole of copper consumed is

The balanced equation gives 2 mol

NO X_{2}

for each mol Cu. The solution turns blue because of

Cu X^{2 +}

. The value 2/3 belongs to dilute nitric acid, which gives NO.