Answer:

(a) Oxygen and Hydrogen in the form of gases.

a

the chemical reaction of this decomposition:

2H2O ---------> 2H2 + O2

this decomposition is called electrolysis and will takes place only when water is containing some electrolyte (for example: salt) and electricity will be used. as this can create high temperature, this will take place in high pressure to balance temperature. because of that pressure, it will generate both oxygen and hydrogen gases.