Answer
Notice Aluminium INCREASES from an oxidation number of 0 to 3+ , because it loses three electrons. So it is oxidized.
Notice Chlorine INCREASES from an oxidation number of -2 to 0 , because it loses two electrons. So it is oxidized.
Notice Sulfur INCREASES from an oxidation number of 2- to 0 , because it loses two electrons. So it is oxidized.
Notice Sr INCREASES from an oxidation number of 0 to 2+ , because it loses two electrons. So it is oxidized.
Work Step by Step
Notice Aluminium INCREASES from an oxidation number of 0 to 3+ , because it loses three electrons. So it is oxidized.
Notice Chlorine INCREASES from an oxidation number of -2 to 0 , because it loses two electrons. So it is oxidized.
Notice Sulfur INCREASES from an oxidation number of 2- to 0 , because it loses two electrons. So it is oxidized.
Notice Sr INCREASES from an oxidation number of 0 to 2+ , because it loses two electrons. So it is oxidized.
