Answer
$1.01\times10^3\ kJ/mol$
Work Step by Step
$I_1=E_{58.4}-E_K=21.23\ eV-10.75\ eV=10.48\ eV$
$10.48\ eV\times\frac{96.485\ kJ}{1\ eV-mol}=1.01\times10^3\ kJ/mol$
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