A quick look at the chemical equation for the formation of water tells us more. 2H2 + O2 = 2H2O It takes two molecules of the diatomic hydrogen gas, combined with one molecule of the diatomic oxygen gas to produce two molecules of water. In other words the ratio of hydrogen to oxygen is 2:1, the ratio of hydrogen to water is 1:1. hope fully this triggers some memories sorry i forgot the rest