Hydrogen peroxide is obtained by the electrolysis of _______.
A. Water
B. Sulphuric acid
C. Hydrochloric acid
D. Fused sodium

Hint: Hydrogen peroxide is an oxidizing agent useful for synthetic purposes and also catalyzes many reactions. It may be prepared from different methods such as from barium peroxide, from electrolytic process, from non-electrolytic process.

Complete answer:
Hydrogen peroxide (having chemical formula, ${{H}_{2}}{{O}_{2}}$) is considered as the simplest peroxide (oxygen-oxygen single bond) present. It is an oxidizing agent and is used for various synthetic purposes such as; it is used as a disinfectant (for its bleaching property), etc.
The preparation of hydrogen peroxide includes laboratory method and industrial method. In laboratory methods of hydrogen peroxide preparation, barium peroxide is acidified and the excess water formed is removed by evaporation under reduced pressure.
While in the industrial method, hydrogen peroxide is prepared from an electrolytic process where thirty percent of ice-cold sulphuric acid is electrolyzed at high current density. Peroxidisulphate is obtained which is later hydrolyzed to form hydrogen peroxide. The reaction is shown below:
$2HSO_{4}^{-}\to {{H}_{2}}{{S}_{2}}{{O}_{8}}+2{{e}^{-}}\text{ (electrolysis)}$
${{H}_{2}}{{S}_{2}}{{O}_{8}}+{{H}_{2}}O\to {{H}_{2}}{{O}_{2}}+{{H}_{2}}S{{O}_{4}}\text{ (hydrolysis)}$

Thus, we can see that hydrogen peroxide is obtained by the electrolysis of sulphuric acid.

Hence, the correct option is B.

Note: It is important to note that; hydrogen peroxide which is prepared from barium peroxide and sulfuric acid cannot be used for a longer duration of time or can’t be stored for a long time. Thus, while preparation of hydrogen peroxide phosphoric acid is usually preferred instead of sulphuric acid.