So the first one is in the format Mg --->Mg^2+ + 2e^-
I am confused as to what is wanted: You state So the first one is in the format Mg --->Mg^2+ + 2e^- Simonizer 1218 answers and submits this exact answer , which in your comments you state is wrong.
After your update: 1. Mg ==> Mg^2+ +2e- 2. Au ==> Au^+ + 1e- 3. Br +1 e- ==> Br^- 4. Mn ==> Mn^2+ + 2e-
But not these: I came up with this and wanted to make sure I've got it right.