Element X and Y are two different elements that are placed in the same group in the Periodic Table of Elements. Which of the following statements is correct about their atoms?

A Atoms of element X and Y have same number of electrons

B Atoms of element X and Y have different number of protons

C Number of neutrons for atom X and Y changes during formation of an ion

D Nucleon number for atom X and Y is the total number of protons and electrons​