A.O2/H2O B.Fe(OH)3/Fe(OH)2 C.MnO-4/MnO2-4 D.Cr2O2-7/Cr3+
A.φ/V=φθ/V+(0.0591pH)/V B.φ/V=φθ/V–(0.0591VpH)/V C.φ/V=φθ/V+(0.0148VpH)/V D.φ/V=φθ/V–(0.0148VpH)/V