Answer
Sodium Arsenate
Arsenic Acid
Magnesium Antimonate
Work Step by Step
$Na$ is Sodium.
$AsO_4$ is Arsenate.
Because $Na_3AsO_4$ is an ionic compound, the name is Sodium Arsenate.
$AsO_4$ is Arsenate.
Because of the leading H, the substance is an acid and is called Arsenic Acid.
$Mg$ is Magnesium.
$SbO_4$ is Antimonate.
Because $Mg_3(SbO_4)_2$ is an ionic compound, the name is Magnesium Antimonate.
