A source of monochromatic radiation of wavelength 400 nm provides 1000 J of energy in 10 seconds. When this radiation falls on the surface of sodium,…

A source of monochromatic radiation of wavelength $\displaystyle 400$ nm provides $\displaystyle 1000$ J of energy in $\displaystyle 10$ seconds. When this radiation falls on the surface of sodium, $\displaystyle x \times 10^{20}$ electrons are ejected per second. Assume that wavelength $\displaystyle 400$ nm is sufficient for ejection of electron from the surface of sodium metal. The value of $\displaystyle x$ is \_\_\_\_. (Nearest integer) $\displaystyle \left(\mathrm{h}=6.626 \times 10^{-34} \mathrm{Js}\right)$