Reaction Quotient Q

[Rachael_1H]

Problem 11.13 from our book states "Write the reaction quotient Q for: 2BCl₃ + 2Hg => B₂Cl₄ + Hg₂Cl₂" and in our answer key the answer is

I am confused at how to get to this answer. I thought that we find Q the same way that we find K: [products]/[reactants]

How does the answer key get to this answer? Could someone please write out the steps and/or explain.

[Chem_Mod]

When writing the equilibrium constant K or the reaction quotient Q, we only consider gases and solutions. Pure liquids and solids are not included in the calculation, therefore, the answer only includes BCl₃ since it is the only gas present in the reaction.