For which of the following reactions is the $\Delta H^o$ value equal to the first ionization energy of $Ca$?

The correct order of second ionization potential of carbon,nitrogen,oxygen and fluorine 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.

Explain why there is a phenomenal decrease in ionisation enthalpy from carbon to silicon.

What factors should be considered to understand the trends in ionization enthalpy values? Explain.

If the successive ionisation energies of an element $A$ are $165$,$190$,$550$ and $595 \ kcal$,respectively,then the ground state electronic configuration of element $A$ is