(i) Cr3+ < Cl–< Mn2+ < Cr
(ii) Mn2+ < Cl–< Cr3+ < Cr
(iii) Cr3+ < Cl–< Cr2O72– < MnO4–
(iv) Mn2+ < Cr3+ < Cl–< Cr
Correct Answer: (ii) Mn2+ < Cl–< Cr3+ < Cr
Explanation: Electrochemical series is a series of chemical substances arranged according to their normal electrode strength. Under the electrochemical series the reduction potential decreases and the reduction potential decreases the reduction potential and reduces the reduction potential, raising the reduction potential.