Chemistry · Structure of atom

When electromagnetic radiation of wavelength \( 300\text{ nm} \) falls on the surface of sodium, electrons are emitted with a kinetic energy of \( 1.68 \times 10^5\text{ J mol}^{-1} \). What is the minimum energy needed to remove an electron from sodium?

1. A
   \( 1.68 \times 10^5\text{ J mol}^{-1} \)
2. B
   \( 3.99 \times 10^5\text{ J mol}^{-1} \)
3. C
   \( 2.31 \times 10^5\text{ J mol}^{-1} \)
4. D
   \( 5.67 \times 10^5\text{ J mol}^{-1} \)