Match these items with their correct definitions. 1 . gas most pure basic substances 2 . elements combined atoms are different 3 . iupac tiny particles of elements 4 . compounds measures gravitational pull 5 . weight no fixed shape or volume 6 . mendeleev co 2 7 . atoms chemist who developed the periodic table 8 . carbon dioxide authority which assigns names to elements

The picture represents the process that produces most of the energy used by living organisms on earth. which process is represented in the picture? a) the magnetic attraction between two hydrogen nuclei. b) the fusion of hydrogen nuclei to produce a helium nucleus in the core of the sun. c) the fission of hydrogen nuclei to produce a helium nucleus in the core of the sun. d) the chemical reaction between hydrogen nuclei to produce a helium nucleus in earth's atmosphere.