What determines how the atoms are organized on the periodic table of elements?

The periodic table of elements arranges all of the known chemical elements in an informative array. Elements are arranged from left to right and top to bottom in order of increasing atomic number. Order generally coincides with increasing atomic mass. The rows are called periods.

Answerthe same as;

The correct answer is:   [c]:     "it is the minimum amount of material needed to sustain a fission  reaction."