Nobel gases has zero electron gain enthalpy
Nobel gas cannot gain or lose electron because they are stable

Thank you so much ….Xyz Abc I understood properly….??
It is bcoz their octat is alredy completed. So in order to gain an electron, they need to absorb energy to make one more energy level for the new electron. So its an endothermic process bcoz of whicb it is positive
They are already stable so they have no need to gain electron and become unstable….