Question

Mohan took pure water for the electrolytic decomposition of water but did not see any bubbles near the electrodes. Why?

Answer 1

Electrolysis of pure water is very low because pure water is a covalent compound and does not ionize to release ions.As there is absence of ionisation no bubbles are seen near the electrodes.Only if water contains some kind of impurities it will ionise to liberate H+ ions and conduct electricity. Only then bubbles can be seen.

Answer 2

Electrolysis of pure water is very low because water is an covalent compound so it can't ionize to release ions hence he could not see any bubbles near the electrodes. To increase the conductivity of water a few drops acid is added acid can  easily ionize to release H+ ions. These H+ions are responsible for the conduction of electricity.