Which equation represents the first electron affinity of chlorine? a. cl(g) + e- → cl - (g) b. 1 2 cl2 (g) + e- → cl - (g) c. cl + (g) + e- → cl(g) d. cl(g) → cl + (g) + e-?

            Option-A [Cl (g) + e⁻  →  Cl⁻ (g)] is the correct answer.

Explanation:
                   First electron affinity is the amount of heat evolved when an electron is added to a neutral atom.
                   Such problems often come in questions related to Born-Haber Cycle topic. Let suppose Mg and Cl₂ is reacted to form MgCl₂ crystal.

Then the Cl₂ gas is first atomized as follow,

                                        Cl₂     →     2 Cl

After atomization an electron is added to neutral chlorine atoms, as,

                                      Cl  +  e⁻    →     Cl⁻

So, option A is correct choice.

Its not chemical its not radiation and its not convection because there is not movement of fluids so it is thermal conduction