In the reaction so2cl2 double arrows so2+ cl2 heat is evolved. what happens when chlorine (cl2) is added to the equilibrium mixture at constant volume?

The chemical reaction is:

SO2Cl2 ⇔ SO2+ Cl2 

This shows that the forward reaction the compound is decomposed to smaller compounds and the backward reaction the larger compound is produced. Adding more chlorine to the mixture when in equilibrium, will shift the equilibrium to the left forming the larger compound.

Yes she is correct. the answer is completely correct

I’d have to say no because without oxygen in the water the fish would all be dead. so if you want to fish for dead fish, pick the ponds with the lowest oxygen concentrations.