The correct increasing order of ionisation enthalpy of $He, Li^{+}, Be^{2+}$ is

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

Which of the following metals is expected to have the highest third ionization enthalpy?

With reference to the concept of ionisation potential,which one of the following sets is correct?

First and second ionization enthalpies of lithium are $520 \text{ kJ mol}^{-1}$ and $7297 \text{ kJ mol}^{-1}$ respectively. Energy required to convert $3.5 \text{ mg}$ lithium $(g)$ into $Li^{2+}(g)$ [$Li(g) \rightarrow Li^{2+}(g)$] is . . . . . . $\text{kJ}$. (nearest integer) [Molar mass of $Li = 7 \text{ g mol}^{-1}$]

Which of the following orders of ionization energy is correct?