Wave Particle Duality

Q. A free atom of iron emits $K_{\alpha }\text{X}$-rays of energy $6.4\text{keV}.$ Calculate the recoil kinetic energy of the atom.
Mass of an iron atom $=9.3\times {10}^{-26}\text{kg}.$

1. $3.9\times {10}^{-4}\text{eV}$
2. $5\times {10}^{-4}\text{eV}$
3. $8.3\times {10}^{-4}\text{eV}$
4. $2.3\times {10}^{-4}\text{eV}$

Q. A free atom of iron emits $K_{\alpha }\text{X}$-rays of energy $6.4\text{keV}.$ Calculate the recoil kinetic energy of the atom.
Mass of an iron atom $=9.3\times {10}^{-26}\text{kg}.$

1. $5\times {10}^{-4}\text{eV}$
2. $3.9\times {10}^{-4}\text{eV}$
3. $2.3\times {10}^{-4}\text{eV}$
4. $8.3\times {10}^{-4}\text{eV}$