A student was asked to calculate the mass of NaCL (in g) needed to creat 500g of 10% NaCL soultion

you need to have a picture of the atom that way we can answer it

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.  

it is reliable if two scientists recorded it