How many ionisation energies can carbon have?

For $Mg$,the values of $\Delta_iH_1$ and $\Delta_iH_2$ are $178 \, kcal \, mol^{-1}$ and $348 \, kcal \, mol^{-1}$ respectively. The enthalpy change for the reaction $Mg \to Mg^{2+} + 2e^-$ is ............. $kcal \, mol^{-1}$.

Calculate the energy required to convert all atoms in $4.8 \ g$ of $Mg$ to $Mg^{2+}$ in the vapour state. $IE_1$ and $IE_2$ of $Mg$ are $740 \ kJ / mol$ and $1450 \ kJ / mol$ respectively.

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:

Discuss and compare the trend in ionisation enthalpy of the elements of group-$1$ with those of group-$17$ elements.

Which statement is correct regarding ionisation potential?