Question

K, Ca and Li metals may be arranged in the decreasing order of their standard electrode potentials as
A) K, Ca and Li
B) Li, K, and Ca
C) Li, Ca and K
D) Ca, Li and K

Answer 1

Hint:The electrode potential is obtained by taking the difference between the potential of the electrode and the electrolyte solution in which the electrode is placed.In the case of the standard electrode potential, the concentration of all species is unity. The standard electrode potential is determined by using the reference electrode that is a standard hydrogen electrode and its electrode potential is zero.

Complete answer:
Here, three metals given are Li, Ca and K oxidizes and liberates electrons.
Using the standard electrochemical series, the reactions and the electrode potential for the given metals are obtained.
Here, the electrode potential for the lithium obtained is \[3.05\,V\].
Here, the electrode potential for the potassium obtained is \[2.93\,V\].
Here, the electrode potential for the calcium obtained is \[2.87\,V\].
From these values, the lowest electrode potential is of calcium and the highest is for lithium.
Therefore, the decreasing electrode potential order is \[{\text{Li > K > Ca}}\].
Here, option(A) K,Ca and Li is incorrect.
Here, option(C) Li, Ca,and K is incorrect.
Here, option(A) Ca, Li, and K is incorrect.
Option(B) Li, K, and Ca is also correct hence, option(B) is the answer to the question.

Note:The metals are electropositive, hence easily undergo the oxidation reaction. More is the electropositive metal greater is its tendency to undergo the oxidation and possess the higher value of oxidation potential.As metals easily oxidized they are acting as reducing agents and one with the highest value of oxidation potential acts as a strong reducing agent.