\(n_{H_2SO_4}=\dfrac{200.4,9\%}{98}=0,1\left(mol\right)\\ H_2SO_4+BaCl_2\rightarrow BaSO_4+2HCl\\ a.n_{BaSO_4}=n_{BaCl_2}=n_{H_2SO_4}=0,1\left(mol\right)\\ n_{HCl}=2.0,1=0,2\left(mol\right)\\ C\%_{ddBaCl_2}=\dfrac{0,1.208}{300}.100\approx6,933\%\\ b.m_{ddsau}=200+300-0,1.233=476,7\left(g\right)\\ C\%_{ddHCl}=\dfrac{0,2.36,5}{476,7}.100\approx1,531\%\)