Question

According to periodic trend, which of the following most likely has the highest ionization energy?
Na
Al
Si
Ar

Answer 1

In my opinion, it is Ar (Argon)
Because as we move from left to right in a period, the value of ionization energy increases and Argon occupies the left most side in the respective period of the Periodic Table

Answer 2

ionization energy increases across the period so Ar