Answer
$H_{2}C_{2}O_{4}$ is acidic
$H_{2}C_{2}O_{4}^{-}$ is amphoteric
$H_{2}C_{2}O_{4}^{2-}$ is basic
$H^{+}$ is acidic
Work Step by Step
$H_{2}C_{2}O_{4}$ can only donate a proton whereas $H_{2}C_{2}O_{4}^{-}$ can donate or accept a proton and $H_{2}C_{2}O_{4}^{2-}$ can only accept a proton. $H^{+}$ is the definition of an acid
