Assertion: The cell potential of mercury cell is 1.35V which remains constant.
Reason: In mercury cell, the electrolyte is a paste of KOH and ZnO.

Options

A. if both assertion and reason are true and the reason is the correct explanation of the assertion.
B. If both assertion and reason are true but reason is not the correct explanation of the assertion.
C. If assertion is true but reason is false
D. If the assertion and reason both are false.

Answer

B

Explanation

`Zn_((s))+Cu_((aq))^(2+)toZn_((aq))^(2+)+Cu_((s))`
As the time passes, the concentration of `Zn^(2+)` keeps on increasing while the concentration of `Cu^(2+)` keeps on decreasing. At the same time voltage of the cell keeps on decreasing. When there is no change in concentration of `Cu^(2+) and Zn^(2+)` ions, voltmeter gives zero reading and this state is known as equilibrium.