Answer:- [tex]Cl_2(g)+2e^-\rightarrow 2Cl^-(aq)[/tex]
Explanations:- In reduction the electrons are accepted and so they are written on the reactant side. When an atom accepts electrons then it forms anion. Chlorine has 7 valence electrons and it needs one more electron to complete it's octet. Since, dichlorine has two Cl atoms and each Cl atom needs one more electron to complete it's octet, two electrons are accepted by dichorine to make aqueous chloride ion. For balancing the equation, there would be two chloride ions as the reactant side has two chlorine atoms.
[tex]Cl_2(g)+2e^-\rightarrow 2Cl^-(aq)[/tex]