The energy required to break one mole of $Cl-Cl$ bonds in $Cl_2$ is $242\;kJ\; mol^{-1}$. the longest wavelength of light capable of breaking a single $Cl-Cl$ bonds is $(c=3 \times 10^4\;ms^{-1}\;and\;N_A=6.02\times 10^{23}mol^{-1})$

Question

$\begin{array}{1 1} (a)\;594\;nm \\(b)\;640\;nm \\ (c)\;700\;nm \\ (d)\;494\;nm \end{array}$