$4FeS_2 + 11O_2 \xrightarrow{t^o}2Fe_2O_3 + 8SO_2$
$n_{FeS_2} = \dfrac{120}{120} = 1(kmol)$
$n_{FeS_2\ pư} = 1.80\% = 0,8(kmol)$
$n_{SO_2} = 2n_{FeS_2\ pư} = 1,6(kmol)$
$m_{SO_2} = 1,6.64 = 102,4(kg)$
2FeS2+11\2O2-to>4SO2+Fe2O3
1----------------------------2 kmol
n FeS2=120\120=1 k mol
H=80%
=>m SO2=2.64.80\100=102,4kg