Asteroids are relatively small to large chunks of celestial body that have dark surface. other asteroids are thought to be rocky and to have a core made of A. Iron or cobalt
B. Cobalt or Nickel
C. Nickel or Zinc
D. Iron or Nickel

answer: atomic mass was originally used to arrange elements on the periodic table, but is no longer used to organize the modern version.

explanation:

originally atomic mass was used to arrange elements on the periodic table from left to right in a row. each column then shows similar properties of elements of a group.

in modern periodic table, the atoms are arranged in increasing atomic number. as atomic number represents the number of protons in an atom which is unique for every atom.