20 mL of calcium hydroxide was consumed when it was reacted with 10 mL of unknown solution of H_2 SO_4. Also 20 mL standard solution of 0.5 M HCl…

$\displaystyle 20$ mL of calcium hydroxide was consumed when it was reacted with $\displaystyle 10$ mL of unknown solution of $\displaystyle \mathrm{H}_2 \mathrm{SO}_4$. Also $\displaystyle 20$ mL standard solution of $\displaystyle 0.5$ M HCl containing $\displaystyle 2$ drops of phenolphthalein was titrated with calcium hydroxide, the mixture showed pink colour when burette displayed the value of $\displaystyle 35.5$ mL whereas the burette showed $\displaystyle 25.5$ mL initially. The concentration of $\displaystyle \mathrm{H}_2 \mathrm{SO}_4$ is $\displaystyle \_\_\_\_$ M.(Nearest integer)