Question

What is the role of manganese dioxide in a dry cell?

(a) It acts as an electrolyte

(b) It acts as the cathode

(c) It acts as an anode

(d) It acts as a depolariser

I have been asked this question in an international level competition.

This interesting question is from Electrochemistry topic in portion Electrochemistry of Chemistry – Class 12

Answer 1

Correct answer is (d) It acts as a depolariser

The explanation is: In a dry cell, in the remaining space between the electrolyte and the graphite cathode, a second paste consisting of ammonium chloride and manganese dioxide is applied. The manganese dioxide acts as a depolariser as it helps to prevent the build-up of hydrogen gas bubbles.