The presence of light element(s)in the Earth’s core is necessary in order to explain the observed density and velocity discrepancy for the core(Anderson and Ahrens,1994).O,Si,S,C and H were suggested as potential candidates based on cosmochemical considerations(Stevenson,1981).High-pressure experiment results,in conjunction with theoretical and cosmochemical evidences,argued that it is difficult for any one of them to account for the core density