Concept:The de Broglie wavelength of a particle is related to its kinetic energy by λ=2mEh.In this formula, the energy E must be expressed in joules, not electron-volts.Explanation:The kinetic energy is given as 100 eV.Convert it to joules using 1 eV=1.6×10−19 J.So, E=100×1.6×10−19=1.6×10−17 J.Now substitute h=6.6×10−34 J s, me=9.1×10−31 kg, and E=1.6×10−17 J into the formula:λ=2×9.1×10−31×1.6×10−176.6×10−34First calculate the value under the square root:2×9.1×10−31×1.6×10−17=2.912×10−47Taking the square root gives 2.912×10−47≈5.40×10−24.Therefore,λ=5.40×10−246.6×10−34≈1.22×10−10 m.This wavelength matches the value in option A.Answer:The wavelength of the de Broglie wave is 1.22×10−10 m.The correct option is A. 1.22×10−10 m.