设生铁中含铁的质量为x.
Fe+H2SO4=FeSO4+H2↑
56 2
x 0.2g
56/x=2/0.2
x=5.6g
铁的质量分数=5.6/6*100%=93.3%
答：生铁中含铁的质量分数是93.3%