Question

Assertion: In the calomel half-cell, the reduction reaction to be considered is Hg${}_2$Cl${}_2$ (s) + 2e${}^{-}$ $\to$ 2Hg (l) + 2Cl${}^{-}$ (aq).
Reason: The Saturated calomel electrode (SCE) is a reference electrode based on the reaction between elemental mercury and mercury(I) chloride.

• A. Both Assertion and Reason are true and Reason is the correct explanation of Assertion
• B. Both Assertion and Reason are true but Reason is not the correct explanation of Assertion
• C. Assertion is true but Reason is false
• D. Assertion is false but Reason is true
• E. Both Assertion and Reason are false

Answer 1

The correct option is A Both Assertion and Reason are true and Reason is the correct explanation of Assertion

The Saturated calomel electrode (SCE) is a reference electrode based on the reaction between elemental mercury and mercury(I) chloride. The aqueous phase in contact with the mercury and the mercury(I) chloride ($H{g}_{2}C{l}_2$, calomel) is a saturated solution of potassium chloride in water.


In the calomel half-cell, the reduction to be considered is:
$H{g}_{2}C{l}_2\left(s\right)+2e^{-}\to 2Hg\left(l\right)+2C{l}^{-}\left(aq\right)$


So the statement is True.