Identify the element having the highest ionization enthalpy.

The correct decreasing order of first ionisation enthalpies of five elements of the second period is

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A:$ The energy required to form $Mg^{2+}$ from $Mg$ is much higher than that required to produce $Mg^{+}$.
Reason $R:$ $Mg^{2+}$ is a small ion and carries more charge than $Mg^{+}$.
In the light of the above statements,choose the correct answer from the options given below:

Observe the following statements.
Statement $(A)$: In general,the ionisation potential value decreases on moving down in the group.
Statement $(B)$: The $1$st ionisation potential of sodium is greater than that of potassium.
Correct answer is:

The first ionisation potential will be maximum for

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