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Chemistry · Structure of atom
हिन्दीWhat is the kinetic energy of an ejected photoelectron from a metal surface if electromagnetic radiation of wavelength \( 242\text{ nm} \) is used, given that the ionisation energy of sodium is \( 494\text{ kJ mol}^{-1} \)?
Correct answer · Option 1
\( 4.93 \times 10^{-20}\text{ J} \)
Explanation
Energy of photon \( E = \frac{hc}{\lambda} = \frac{6.626 \times 10^{-34} \times 3 \times 10^8}{242 \times 10^{-9}} = 8.21 \times 10^{-19}\text{ J} \). Threshold energy \( W = \frac{494 \times 10^3}{6.022 \times 10^{23}} = 8.20 \times 10^{-19}\text{ J} \). K.E = \( E - W = 4.93 \times 10^{-20}\text{ J} \).
