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

The correct values of ionization enthalpies (in $kJ \ mol^{-1}$) of $Si, P, Cl$ and $S$ respectively are

The first ionisation energies of alkaline earth metals are higher than those of the alkali metals. This is because

The first ionization enthalpy of $Na$,$Mg$ and $Si$,respectively,are: $496, 737$ and $786 \ kJ \ mol^{-1}$. The first ionization enthalpy $(kJ \ mol^{-1})$ of $Al$ is

The given electronic configurations are for elements $X$,$Y$,and $Z$. Note that these configurations represent ions of the elements:
$X = [Ne] \, 3s^2 \, 3p^5$
$Y = [Ne] \, 3s^2 \, 3p^6$
$Z = [Ne] \, 3s^2 \, 3p^4$
Determine the correct statement regarding the energy changes associated with these configurations.

When first ionisation energy is plotted against the atomic number,the peaks in the curve are occupied by