Question

if H2+O2 gives us water(H2O) then how does hydrogen peroxide(H2O2) form? Please explain.

Answer 1

Hydrogen Peroxide, which is also known as heavy water, is available in very less amount in nature, which is the main source to extract it is not a safer way to produce it in laboratories.
One of some common methods to obtain Hydrogen Peroxide is by treating Barium Peroxide with Nitric Acid. An another improved version of this process used Hydrochloric Acid, followed by addition of Sulphuric Acid to precipitate the Barium Sulphate as byproduct.
One litre of water(H2O) solution contains only 0.5% of Hydrogen Peroxide.
Due to which it is needed to be separated from H2O by various methods executed in many steps. This is a reason due to which Hydrogen Peroxide is very costly too.