Answer:
Step-by-step explanation:
a2SO4 has two sodium (Na) atoms with an oxidation charge of plus 1 each and an overall oxidation value of plus 2. Add together the oxidation values for all known species. Subtract the summed value from the overall charge of the compound. For example, Na2SO4, Na2 yields 2 (plus 1) + 4(minus 2) = minus 6.