The \( 25 mL \) of a \( 0.15 M \) solution of lead nitrate, \( Pb \left( NO _{3}\right)_{2} \) reacts with all of the aluminium sulphate, \( Al _{2}\left( SO _{4}\right)_{3} \), present in \( 20 mL \) of a solution. What is the molar concentration of the \( Al _{2}\left( SO _{4}\right)_{3} ? \)
