The surface of sodium metal is irradiated with radiation of wavelength x nm. The kinetic energy of ejected electrons is 2.8 × 10^-20 J. The work…

The surface of sodium metal is irradiated with radiation of wavelength $\displaystyle x \mathrm{~nm}$. The kinetic energy of ejected electrons is $\displaystyle 2.8 \times 10^{-20} \mathrm{~J}$. The work function of sodium is $\displaystyle 2.3$ eV. The value of $\displaystyle x$ is $\displaystyle \_\_\_\_$ $\displaystyle \times 10^2 \mathrm{~nm}$. (Nearest integer) (Given : $\displaystyle \mathrm{h}=6.6 \times 10^{-34} \mathrm{~J} \mathrm{~s} ; 1 \mathrm{eV}=1.6 \times 10^{-19} \mathrm{~J} ; \mathrm{c}=3.0 \times 10^8 \mathrm{~m} \mathrm{~s}^{-1}$ )