Chapter 9.1, Problem 9.3P

Which of the following species can be Brønsted-Lowry acids: $\left(\text{a}\right)\text{ HI; }\left(\text{b}\right){\text{ SO}}_4^{2-}\text{; }\left(\text{c}\right){\text{ H}}_{\text{2}}{\text{PO}}_{\text{4}}{}^{\text{-}}\text{; }\left(\text{d}\right){\text{ Cl}}^{\text{-}}\text{?}$
More Practice: Try Problems 9.21, 9.22.