ANSWER
[tex]\text{BCl}_3+Cl_2^-\rightarrow BCl_5_{}[/tex]STEP-BY-STEP EXPLANATION:
Firstly, we need to write the chemical formula for Boron (III) chloride
[tex]BCl_3_{}[/tex]The reaction between boron(III)chloride and chloride is called a combination reaction.
A combination reaction is a reaction in which two reactants combine to form one product.
[tex]\text{BCl}_3+Cl^-_2\text{ }\rightarrow BCl_5[/tex]