This is the 12559th most frequent German word.
wasserstoff
Hydrogen.
Subject of the sentence, referring to 'hydrogen' as a chemical element.
Wasserstoff ist das leichteste chemische Element.
Hydrogen is the lightest chemical element.
Object of the preposition 'als', indicating its use as fuel.
Im Auto wird Wasserstoff als Brennstoff verwendet.
In the car, hydrogen is used as a fuel.
Object of the preposition 'von', indicating its potential role in energy.