A spherical copper particle has about 125 atoms. If the atomic radius of copper is $140 \mathrm{pm}\left(1 \mathrm{pm}=10^{-12} \mathrm{~m}\right)$, the diameter of the particle is close to the wavelength of

• A

  green light.
• Correct answer
  B

  electron beam of energy 1.4 eV .
• C

  sound waves of frequency 340 Hz travelling in air at room temperature.
• D

  x-rays of energy 12.40 keV .

Hence, the correct answer is option: 'B'.