In which of the following reactions conc. H2SO4 is used as an oxidising reagent?

An oxidizing agent reduces itself and oxidation state of central atom decreases.


2HI + H2SO4→ I2 + SO2 + 2H2O


Oxidation state of central atoms:


HI = -1


H2SO4 = -6


I2= 0


SO2 = -4


Cu + 2H2SO4→ CuSO4 + SO2 + 2H2O


Oxidation state of central atom:


Cu = 0


H2SO4 = -6


CuSO4 = +2


SO2 = +4


Hence the correct options are (ii) and (iii).

1