20g of sample of $Ba(OH)_2$ is dissolved in 50c.c of 0.1N HCl solution.The excess of HCl has titrated with 0.1NaOH.The volume of NaOH used was 20c.c.Calculate percentage of $Ba(OH)_2$ in the sample

Question

$\begin{array}{1 1}(a)\;1.28\%& (b)\;12.8\% \\(c)\;25.6\%&(d)\;0.128\%\end{array}$