Answer
$46.3\%$
Work Step by Step
$TiO_{2}$ is the limiting reactant. Theoretical yield of $TiCl_{4}$ is the mass of $TiCl_{4}$ produced based on the amount of $TiO_{2}$.
$50.0\,g\times\frac{1\,mol\,TiO_{2}}{79.866\,g}\times\frac{1\,mol\,TiCl_{4}}{1\,mol\,TiO_{2}}\times\frac{189.679\,g}{1\,mol\,TiCl_{4}}=118.748\,g$
$\text{% yield}=\frac{\text{Actual yield}}{\text{Theoretical yield}}\times100\%=\frac{55.0\,g}{118.748\,g}\times100\%=46.3\%$
