Electromagnetic radiation of wavelength `242` nm is just sufficient to ionise a sodium atom. Calculate the energy corresponding to this wavelength and the ionisation potential of Na.

Explanation

Energy of sodium (E)
`(N_(A)hc)/lambda`
`((6.023xx10^(23)mol^(-1))(6.626xx10^(-34)Js)(3xx10^(8)ms^(-1)))/(242xx10^(-9)m)`
`4.947xx10^(5) Jmol^(-1)`
`497.7xx10^(3) J mol ^(-1)`
`494 kJmol^(-1)`
`494 Kjmol^(-1)`