An Electromagnetic radiation of wavelength `242` nm is just sufficient to ionise a sodium atom .Calculate the ionisation energy of sodium in `KJ mol^(-1)`.

Answer

A, D

Explanation

`E=(hc)/lambda=(6.62xx10^(-34)jsxx10^(8) ms^(-1))/(242 "nm" xx10^(-9)mJ "atom"^(-1))`
`E = (hc)/(lambda) = (6.62 xx 10^(-34) J s xx 10^(8) m s^(-1))/(424 nm xx 10^(-9) "m j atom" ^(-1))`
`= 494 kJ mol^(-1)`