In: Physics
1) c = frequency*wavelength
c = 299792458 m/s
wavelength = 505nm = 5.05e-7 m
so frequency = 5.94e14 Hz
2)
E = h*frequency = 3.93e-19J
1 J = 6.26e18 eV
so this energy in eV = 3.93e-19*6.24e18 = 2.452 eV
3)
(1/2)mv^2 = 3.93e-19
so, v = 9.096 mm/s