Answer:
                       %age Yield =   96 %
Explanation:
                     The balance chemical equation for given double replacement reaction is,
                       Ba(NO₃)₂ + Na₂SO₄ → BaSO₄ + 2 NaNO₃
Step 1: <u>Calculate moles of Ba(NO₃)₂:</u>
Moles  =  Mass / M.Mass
Moles  =  75.1 g / 261.33 g/mol
Moles  =  0.2873 moles of Ba(NO₃)₂
Step 2: <u>Find out moles of BaSO₄ formed:</u>
According to balance chemical equation,
                   1 mole of Ba(NO₃)₂ produced  =  1 mole of BaSO₄
So,
         0.2873 moles of Ba(NO₃)₂ will produce  =  X moles of BaSO₄
Solving for X,
                        X  =  0.2873 mol × 1 mol / 1 mol
                        X  =  0.2873 moles of BaSO₄
Step 3: Calculate Theoretical Mass of BaSO₄:
Mass  =  Moles × M.Mass
Mass  =  0.2873 mol × 233.38 g/mol
Mass  =  67.07 g of BaSO₄
Step 4: <u>Calculate %age Yield as:</u>
                  Theoretical Yield  =  67.07 g
                   Actual Yield  =  64.4 g
                   %age Yield  =  <u>???</u>
Formula Used:
                    %age Yield  =  (Actual Yield ÷ Theoretical Yield) × 100
Putting Values,
                    %age Yield  =  (64.4 g ÷ 67.07 g) × 100
                    %age Yield =  96.01 % ≈ 96 %