in the modern periodic table elements are arranged by: valence electrons atomic number number of isotopes…

in the modern periodic table elements are arranged by: valence electrons atomic number number of isotopes atomic mass

in the modern periodic table elements are arranged by: valence electrons atomic number number of isotopes atomic mass

Answer

Brief Explanations:

In the modern periodic table, elements are arranged in ascending order of their atomic numbers. This arrangement helps in understanding the periodic trends and chemical - physical properties of elements.

Answer:

B. atomic number