Which of the following gaseous atoms has the highest value of $IE$?

Which one of the following elements has the highest ionisation energy?

The incorrect statement among the following is:

In the given graph,which point represents an alkali metal with the least atomic number?

The correct trend in the first ionization enthalpies of the elements in the $3^{rd}$ period of periodic table is:

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: