The ionization potentials of $Li$ and $K$ are $5.4 \ eV$ and $4.3 \ eV$ respectively. The ionization potential of $Na$ will be .............. $eV$.

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 atomic numbers of $V, Cr, Mn$ and $Fe$ are $23, 24, 25$ and $26$ respectively. Which of these elements will have the highest second ionization enthalpy?

The incorrect statement among the following is:

The element having the greatest difference between its first and second ionization energies is:

Which one of the following has the lowest ionization energy?