When gasses are under the same conditions (same temperature and pressure), the volume relationships between gasses, give the coefficients of the balanced equation.
So, [tex]1Cl_2 + 3F_2 ---\ \textgreater \ 2 (Product)[/tex]
Now, we can find the product using this balanced chemical equation.
On reactant side, we have :
[tex]1Cl_2 + 3F_2 = 2Cl + 6F atoms[/tex]
Product will contain 2Cl + 6F atoms
[tex]2Cl + 6F = 2(Cl + F_3) = 2ClF_3[/tex]
= 2(Product)
So, The formula of the product is = [tex]ClF_3[/tex]