29 . Commercially , hydrogen peroxide is generally sold as its percentage solution . For example 10 volume of hydrogen peroxide means that 1 liter of this hydrogen peroxide solution will give 10 liter of oxygen at STP
30 . Hydrogen peroxide decomposes to form water and oxygen , on exposure to sunlight . Hence it is stored in wax-lined glass or plastic vessel
31 . D2O is called heavy water . It is manufactured by electrolytic enrichment of normal water . It is used as moderator in nuclear reactor