## Chemistry: The Central Science (13th Edition)

$HS^-$ is the stronger base.
$HS^-$ and $H{SO_4}^-$ are, respectively, the conjugate bases of $H_2S$ and $H_2SO_4$. Since $H_2SO_4$ is stronger than $H_2S$, and the stronger the acid, the weaker its conjugate base, $HS^-$ is the stronger base.