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# Conditions for ranking of negative ion discharge order

My teacher told us about the negative ion discharge order

$$\ce{SO4^2-} < \ce{NO3-} < \ce{OH-} < \ce{Cl-} < \ce{Br-} < \ce{I-}$$

in the sense which ion would discharge to electrodes first in a mixture. For example, $$\ce{NaCl(aq)}$$ solution where $$\ce{Cl-}$$ ion would get discharged before $$\ce{OH-}$$ ion. Similarly, $$\ce{H+}$$ ion would be reduced to $$\ce{H2}$$ (gets to the cathode before $$\ce{Na+}$$ ion).

What factors does this order depend upon?