13. Classify as man-made or natural extinction: Massive impact from asteroid or comet. O Both
O Neither
O Natural Extinction
O Man-made

Natural extinction

Explanation:

Man doesn't play a part in space objects causing extinction

mention the spill to the teacher clean the area and throw the broken pieces away

explanation:

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.