даноm(ppa HCOOH) = 100 gW(HCOOH) = 30%---------------------------------------V(H2)-?m(HCOOH) = 100*30% / 100% = 30 g2HCOOH+Mg-->(HCOO)2Mg+H2M(HCOOH) = 46 g/moln(HCOOH) = m/M = 30 / 46 = 0.65 mol2n(HCOOH) = n(H2)n(H2) = 0.65 / 2 = 0.325 molV(H2) = n*Vm = 0.325 * 22.4 = 7.28 Lответ 7.28 л