Verified answer

      15г                                            Х г

      BaCl2      +       H2SO4      =     BaSO4     +    2HCl

n = 1 моль                                  n = 1 моль

Mr = 208 г/моль                         Mr = 233 г/моль

m = 208 г                                   m = 233 г

15 г BaCl2      -     Х г BaSO4

208 г BaCl2    -     233 г BaSO4

m(BaSO4) = 15 * 233 / 208 = 16,8 г