Suppose a gaseous mixture of $He$, $Ne$, $Ar$ and $Kr$ is treated with photons of the frequency appropriate to ionize $Ar$. What ion$(s)$ will be present in the mixture?

The first four $I.E.$ values of an element are $284, 412, 656$ and $3210 \ kJ \ mol^{-1}$. The number of valence electrons in the element are

In which of the following electronic configurations will there be a large difference between the second and third ionization energy?

Which among the following elements has the highest first ionization enthalpy?

Electronic configurations of four elements $A$,$B$,$C$,$D$ are given below:
$A$) $1s^2 2s^2 2p^6 3s^1$
$B$) $1s^2 2s^2 2p^6 3s^2 3p^1$
$C$) $1s^2 2s^2 2p^6 3s^2$
$D$) $1s^2 2s^2 2p^6 3s^2 3p^2$
The correct order of first ionization enthalpy of these elements is:

The electronic configuration with the highest ionization enthalpy is