Calculate the \( \mathrm{pH} \) of \( 0.1 \mathrm{M} \mathrm{Na}_{3...

Calculate the \( \mathrm{pH} \) of \( 0.1 \mathrm{M} \mathrm{Na}_{3} \mathrm{~A} \) of solution (salt of a tribasic acid \( \mathrm{H}_{3} \mathrm{~A} \) ). Assume only first step hydrolysis to be significant. Given : \( \mathrm{K}_{\mathrm{a}_{1}}, \mathrm{~K}_{\mathrm{a}_{2}} \& \mathrm{~K}_{\mathrm{a}_{3}} \) for \( \mathrm{H}_{3} \mathrm{~A} \) are \( 10^{-4}, 10^{-7} \& 10^{-9} \) respectively.