How is the modern periodic table organized as one goes across a row from left to right?
a) by decreasing number of valence electrons
b) by increasing number of neutrons
c) by increasing atomic number
eliminate
d) by increasing atomic mass

Option (C) is the correct answer.

Explanation:

Elements in a periodic table are arranged according to the increase in atomic number.

So, when we move from left to right in a periodic table then there occurs an increase in atomic number because there occurs an increase in the number of electrons of the atoms.

And, in neutral atoms the number of electrons and number of protons are the same.

Therefore, we can conclude that modern periodic table organized by increasing atomic number as one goes across a row from left to right.

4 = c

Explanation: