m(Al) = 200 mg = 0.2 g

V(H2) - ?
n(Al) = 0.2 g / 27 g / mol = 0.007 mol

0.007 mol                                x mol

2Al + 3H2SO4 = Al2(SO4)3 + 3H2

2 mol                                        3 mol

2:0.007 = 3:x

2x = 0.021

x = 0.0105

V(H2) = 0.0105 mol * 22.4 l / mol = 0.2352 l = 235.2 ml

Ответ: 235.2 ml .