Which of the following has the least ionization potential?

The incorrect relation among the following is

The order of ionisation potential between $He^{+}$ ion and $H$ atom (both species are in gaseous state) is

Which of the following atomic species has maximum ionisation energy?

Which of the following orders regarding ionization energy is correct?

The first ionisation potential $(IP)$ of the elements $Na$,$Mg$,$Si$,$P$,$Cl$ and $Ar$ are $5.14$,$7.65$,$8.15$,$10.49$,$12.97$ and $15.76 \ eV$,respectively. The $IP$ (in $eV$) of $K$ is closest to