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 associated with a photon of 242nm =`(6.62xx10^(-34)xx3.0xx10^(8))/(242xx10^(-9)`=`8.21xx10^(-19)("joule")`
`because` 1atom of Na for ionisation requires `=8.21xx10^(-19)J`
`therefore6.023xx10^(23) ` atoms of Na for ionisation requires `=8.21xx10^(19)xx6.023xx10(23)`
`=49.45xx10(4)J`=`494.5 KJ mol_(-1)`