Which of the following processes do not involve absorption of energy ?

The amount of energy released when $1\times {10}^{10}$ atoms of chlorine in vapour state are converted to ${\mathrm{Cl}}^{-}$ ions according to the equation,

$\mathrm{Cl}\left(\mathrm{g}\right) + {\mathrm{e}}^{-} \to {\mathrm{Cl}}^{-} \left(\mathrm{g}\right) \mathrm{is} 57.86 \mathrm{x} {10}^{-10} \mathrm{J}.$

Calculate the electron gain enthalpy of chlorine atom in terms of $\mathrm{eV}$ per atom.