I want to test the ability of students to read a passage and answer questions about it. Could you please come up with a good question for the passage "In the absence of atmospheric oxygen (O2), in deep geological conditions prevailing far away from Earth atmosphere, hydrogen (H2) is produced during the process of serpentinization by the anaerobic oxidation by the water protons (H+) of the ferrous (Fe2+) silicate present in the crystal lattice of the fayalite (Fe2SiO4, the olivine iron-endmember). The corresponding reaction leading to the formation of magnetite (Fe3O4), quartz (SiO2) and hydrogen (H2) is the following:"? 

The element from the periodic table of elements with an atomic number of 8 is called?