Which force was the first to be discovered?

A. Gravity
B. Weak nuclear force
C. Strong nuclear force
D. Electromagnetic force

h let me think about that

the answer is either b or c

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.