Some Basic Concepts Of Chemistry

\(20 \mathrm{~mL}\) of calcium hydroxide was consumed when it was reacted with \(10 \mathrm{~mL}\) of unknown solution of \(\mathrm{H}_{2} \mathrm{SO}_{4}\). Also \(20 \mathrm{~mL}\) standard solution of \(0.5 ~\mathrm{M} ~\mathrm{HCl}\) containing 2 drops of phenolphthalein was titrated with calcium hydroxide, the mixture showed pink colour when burette displayed the value of \(35.5 \mathrm{~mL}\) whereas the burette showed \(25.5 \mathrm{~mL}\) initially. The concentration of \(\mathrm{H}_{2} \mathrm{SO}_{4}\) is _____________ M. (Nearest integer)