What maximum wavelength is required for a photon to dissociate : `X_(2)(g) rarr 2X(g)` if bond energy of `X-X` bond is `240kJ//mol` ?

Explanation

One photon breaks one bond only
Energy of break `N_(A)` bonds `=240xx10^(3)J`
Energy of break `1` bond `=(240xx10^(3))/(N_A)J`
`implies(240xx10^(3))/(N_A)= (hc)/(lambda_(max))=(6.626xx10^(-34)xx3xx10^(8))/(lambda_(max))=lambda_(max)=4966 Å`