Which of the following elements has the lowest ionization potential?

The correct order of the first ionization enthalpy is

What are the various factors due to which the ionization enthalpy of the main group elements tends to decrease down a group?

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

Given below are two statements $:$
Statement $(I) :$ The first ionisation enthalpy of group $14$ elements is higher than the corresponding elements of group $13.$
Statement $(II) :$ Melting points and boiling points of group $13$ elements are in general much higher than those of the corresponding elements of group $14.$ In the light of the above statements,choose the most appropriate answer from the options given below $:$

Which one of the following statements is incorrect in relation to ionisation enthalpy?