Missing question: calcium chloride dihydrate, barium hydroxide octahydrate, magnesium sulfate heptahydrate.
Sodium sulfate decahydrate - Na₂SO₄×10H₂O. Sodium has oxidation number +1 and sulfate -2.
Calcium chloride dihydrate - CaCl₂×2H₂O. Calcium has oxidation number +2 and chlorine -1.
Barium hydroxide octahydrate Ba(OH)₂×8H₂O. Barium has oxidation number +2 and hydroxide -1.
Magnesium sulfate heptahydrate MgSO₄×7H₂O. Magnesium has oxidation number +2.