254. Make a material and an electronic balance the following redox reactions: H2 SO4 + H2S S0 + H2O; HC1 + HMnO4 MnC12 + C12 + H2O; H2SO3 + C12 + H2O H2SO4 + HC1; H2SO4 + Cu CuSO4 + SO2 + H2O.