Question

In water voltameter, the electrolysis of _________ takes place.
A. ${{H}_{2}}O$
B. ${{H}_{2}}{S}{{O}_{4}}$
C. ${{H}_{2}}O$ and $H_2SO_4$ both
D. ${{H}_{2}}$ and ${{O}_{2}}$

Answer 1

Hint: To answer this question, we need to be aware of the proper structure of a water voltameter and how it works. We also require a basic understanding of electrolysis.

Complete Step by Step Answer:
Water voltameter is a scientific apparatus that operates based on principles of electrolysis. Electrolysis refers to the breakdown of electrolyte into its chemical parts when an electric current passes through it.
The instrument has two glass tubes that have the same volume. One end of each glass tube is fitted with a platinum plate. Both the plates are connected to either side of a power source such as a cell. The plate attached to the positive terminal of the power supply is called the “anode” and the one attached to the negative terminal of the power supply is called the “cathode”. It contains pure water as its electrolyte.

When an electric current is passed through the electrolyte, i.e. water, it starts to decompose into its elemental components (oxygen gas and hydrogen gas). According to the electrolytic principle, negative charge collects at the anode while positive charge collects at the cathode. So hydrogen gas is liberated at the cathode and oxygen gas is liberated at the anode.
So, the correct answer option A.

Additional information: Water voltameter is often used as a demonstration of stoichiometric principles, as the two-to-one ratio of the volumes of hydrogen and oxygen gas produced by the apparatus illustrates the chemical formula of water, ${{H}_{2}}O$.

Note: As pure water can’t conduct electricity, a little amount of soluble salt is required in the solution for the process of electrolysis to conduct.