Starting from the $1^{st}$,the successive ionization potentials of an element are respectively $5.98, 18.8, 28.4, 120.1, 154 \ eV$. The element is

Would you expect the first ionization enthalpies for two isotopes of the same element to be the same or different? Justify your answer.

In a group of elements,as the atomic number increases,which of the following is $NOT$ observed?

Given below are two statements:
Statement $(I)$: The first ionisation enthalpy of the elements $Na$,$Mg$,$Cl$ and $Ar$ follows the order $Na > Mg > Cl > Ar$.
Statement $(II)$: Among $Ca$,$Al$,$Fe$ and $B$,the third ionisation enthalpy is very high for $Ca$.

Why does the successive ionization enthalpy of an element increase in the order: $1^{st} < 2^{nd} < 3^{rd}$?

Which of the following elements has the highest value of first ionization enthalpy $(\Delta_i H_1)$?