IP₁ of magnesium is xkcal / mole. The energy required for the process ${\mathrm{Mg}}_{\left(\mathrm{g}\right)}\to {\mathrm{Mg}}_{\left(\mathrm{g}\right)}^{+2}+2{\mathrm{e}}^{-}$ will be approximately _____k cal.

Now, take a look at the reaction

Mg → Mg²⁺ + 2e⁻

So, to take out two electrons from Mg, we have to provide energy.

Therefore, total energy required will be IP₁+IP₂+IP₃ = 3x K.Cal/mole.