The correct answer is 0.39nm.
A periodic wave's spatial period, or the distance across which the wave's form repeats, is defined by its wavelength. It is a characteristic of both travelling and standing waves as well as other spatial wave patterns, and it is the distance between two adjacent corresponding points of the same phase on the wave.
Speed of proton = c= 2.0 × 10^6 m/s
The threshold energy of the proton is E = 3.4 x 10^-18 J
The proton's wavelength is expressed as follows:
λ=hc/E
h is the Planck constant in this situation.
Now substituting the values,
λ= (6.63x10^-34J/sx 2.0 × 10^6 m/s)/3.4x 10^-18 J
=3.9x 10^-10 m
=0.39nm
To learn more about Plancks constant refer the link:
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