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 × 10²⁰” 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) $\left(\mathrm{h}=6.626\times {10}^{-34}\mathrm{Js}\right)$