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, $x \times 10^{20}$ electrons are ejected per second. Assume that wavelength 400 nm is sufficient for ejection of electron from the surface of sodium metal. The value of x is $\_\_\_\_$ .
(Nearest integer) ( $\mathrm{h}=6.626 \times 10^{-34} \mathrm{Js}$ )