Consider the following relations for `emf` of a electrochemical cell
(i) emf of cell = (Oxidation potential of anode)-(Reduction potential of cathode)
(ii) emf of cell = (Oxidation potential of anode)+(Reduction potential of cathode)
(iii) emf of cell = (Reduction potential of anode)+(Reduction potential of cathode)
(iv) emf of cell = (Oxidation potential of anode)-(Oxidation potential of cathode)
Which of the above realtions are correct?

Options

A. (i) and (iii)
B. (i) and (ii)
C. (iii) and (iv)
D. (ii) and (iv)

Answer

B

Explanation

Since oxidation takes places at anode whikle reduction occurs at cathode, there are three ways to calculate the `emf` of an electrochemical cell:
`E_("cell")^(@) = E_("anode")^(@)("oxid")+E_("cathode")^(@)("red")`
or `E_("cell")^(@) = E_("anode")^(@)("oxid")-E_("cathode")^(@)("oxid")`
or `E_("cell")^(@) = E_("cathode")^(@)("red")+E_("anode")^(@)("oxid")`