(Solved): 4. Phosphoric acid has a formula of H3PO4 and has a Ka1 of 7.5103,Ka2 of 6.21 ...

4. Phosphoric acid has a formula of $${\mathrm{H}}_3{\mathrm{PO}}_4$$ and has a $${\mathrm{K}}_{\mathrm{a}1}$$ of $$7.5\times 10^{?3},{\mathrm{K}}_{\mathrm{a}2}$$ of $$6.2\times 10^{?8}$$, and $${\mathrm{K}}_{\mathrm{a}3}$$ of $$4.2\times 10^{?13}$$ at $$25^{?}\mathrm{C}$$. Which of the following statements is true concerning the species present in a $$0.1\mathrm{M}{\mathrm{H}}_3{\mathrm{PO}}_4(\mathrm{aq})$$ solution? I. $$\left[{\mathrm{H}}_2{\mathrm{PO}}_4{}^{?}\right]>\left[{\mathrm{HPO}}_4{}^{2?}\right]$$. II. The strongest conjugate base involved is the $${\mathrm{PO}}_4{}^{3?}(\mathrm{aq})$$ species. III. $${\mathrm{HPO}}_4{}^{2?}(\mathrm{aq})$$ is a stronger acid than $${\mathrm{H}}_2{\mathrm{PO}}_4{}^{?}$$(aq). IV. The $$\mathrm{pH}$$ of this solution is mainly determined by $${\mathrm{K}}_{\mathrm{a}2}$$.