For the following reactions
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Assign oxidation states for all atoms
Identify which atoms are oxidized and which are reduced
Write the oxidation and reduction half reactions
Determine the total number of electrons transferred

2 Mg + O₂ → 2MgO. 2VCL4+8HBr=2VBr3+8HCL+Br2. As2O3+2HNO3+2H2O=2H3AsO4+N2O3