Answer
$5.57\times10^{9} kJ/mol.$
Work Step by Step
Energy of one mole of photons = $hν\times\frac{6.022\times10^{23}}{1 mole} = \frac{hc}{λ}\times\frac{6.022\times10^{23}}{1 mole}$
h = $6.626\times10^{-34}Js$
c = $3.00\times10^{8}ms^{-1}$
λ = $2.15\times10^{-5} nm = 2.15\times10^{-5}\times10^{-9}m = 2.15\times10^{-14}m$
E = $\frac{6.626\times10^{-34}Js\times3.00\times10^{8}ms^{-1}}{2.15\times10^{-14}m}\times\frac{6.022\times10^{23}}{1 mole}$ = $5.57\times10^{12} J/mol$ = $5.57\times10^{9} kJ/mol.$
