Electron affinity depends on

Which of the following will have the most negative electron gain enthalpy and which the least negative?
$P, S, Cl, F$
Explain your answer.

Consider the following conversions:
$(i) \, O_{(g)} + e^- \to O_{(g)}^{-}, \Delta H_1$
$(ii) \, F_{(g)} + e^- \to F_{(g)}^{-}, \Delta H_2$
$(iii) \, Cl_{(g)} + e^- \to Cl_{(g)}^{-}, \Delta H_3$
$(iv) \, O_{(g)}^{-} + e^- \to O_{(g)}^{2-}, \Delta H_4$
Based on the given information,which statement is incorrect?

The electron affinity of chlorine is $3.7 \ eV$. $1 \ g$ of chlorine is completely converted to $Cl^-$ ion in a gaseous state. $(1 \ eV = 23.06 \ kcal \ mol^{-1})$. Energy released in the process is $...... \ kcal$.

Identify the element having positive electron gain enthalpy.

Which of the following has the highest electron affinity?