We know $\ce{H2}$ is formed with covalent bonds (same withjust as $\ce{O2}$ is formed via covalent bonding). Hence, theythese molecules gain some stability. SoIn spite of this stability, why do they react with each other to form $\ce{H2O}$ or $\ce{H2O2}$?
Improved title and body. Removed irrelevant tag.