are in the same period. are in the same family. have the same number of electrons. have the same atomic mass number.
I am hesitating between 4 options to answer the following question, which option should I choose?
Question: Certain elements with similar chemical and physical properties are found in the same column in the Periodic Table of the Elements. These chemicals
Possibilities:
- are in the same period.
- are in the same family.
- have the same number of electrons.
- have the same atomic mass number.

are in the same family.