have the same reactivity. decrease in atomic mass. increase in atomic number. have the same number of electrons.
I am hesitating between 4 options to answer the following question, which option should I choose?
Question: Reading from left to right, elements in the same period on the Periodic Table of the Elements
Possibilities:
- have the same reactivity.
- decrease in atomic mass.
- increase in atomic number.
- have the same number of electrons.

increase in atomic number.