Electromagnetic radiations of wavelength 242 nm is just sufficient to ionize Sodium atom. Then the ionization energy of Sodium in kJ mole−1 is
The correct option is A
494.65
I.E. of one sodium atom = hC/λ
& I.E. of one mole Na atom hC/λ NA
= 6.62 × 1034 × 3 × 108 × 6.02 × 1023/(242 × 10−9 )= 494.65kj.mol