Verified Solution • 2025–26 Session moderate

QJEEM21Chd64a: JEE Main 2021 Chemistry - Class 11 JEEM21Chd64a Solution: A source of monochromatic radiation of wavelength 400 nm…

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)

(h = 6.626 × 10−34 Js)

Step-by-Step Verified Solution

Total energy provided by

Source per second = 100010=100 J

Energy required to eject electron = hcλ

= 6.626×10−34400×10−9×3×108

Number of electrons ejected

= 1006.626×10−34×3×108400×10−9

= 400×10−7×10266.626×3

= 40×10−206.626×3

= 2.01×1020

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