The work function of sodium metal is $4.41 \times 10^{-19} \mathrm{~J}$. If photons of wavelength 300 nm are incident on the metal, the kinetic energy of the ejected electrons will be ( $\mathrm{h}=6.63 \times 10^{-} \left.{ }^{34} \mathrm{~J} \mathrm{~s} ; \mathrm{c}=3 \times 10^8 \mathrm{~m} / \mathrm{s}\right)$ $\_\_\_\_$ $\times 10^{-21} \mathrm{~J}$.