11,2 г                                                              Х л

  2Fe        +        6H2SO4     =   Fe2(SO4)3 + 3SO2 + 6H2O

n = 2 моль                                                       n = 3 моль

Mr = 56 г/моль                                               Vm = 22,4 л/моль

m = 112 г                                                        V = 67,2 л

11,2 г Fe    -   Х л SO2

112 г Fe    -   67,2 л SO2

V(SO2) = 11,2 * 67,2 / 112 = 6,72 л