Potassium-42 is a form of the element Potassium. It is used in medicine and decays over time. A sample of 800 mg is tested. After 30 hours, there Is about 140 mg remaining.
Which represents the rate of decay?
O A k=
In(0.175)
30
Ock=-
In(140)
24000
B. k =
In(5.714)
30
OD. k=-
In(800)
4200

hi

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.