H2O2 is unstable because the extra oxygen molecule is always trying to "escape". Light, heat, or open air facilitates the escape, and it turns into H2O or plain water.
The brown bottled stuff (3%) has additives to make it more stable, and extend shelf life.
Disclaimer: I am not a chemist.
I've kept H2O2 in the brown bottles for 3 years and more.
I've kept food grade H2O2 (35%) in the white bottles, in the fridge for up to a year before, with no degradation.
The 35% H2O2 will cause chemical burns, so exercise care when diluting and handling.
Thanx. I’ll check out what I’vr got it the fridge & be back
Thanx for the info