The system we will be observing in this lab involves the cobalt(II) ion. This ion can form two complexes, one with water and one with the chloride
ion (CI'). Below is a reaction showing the addition of chloride ions to the
cobalt - water complex.
Co(H2016 + Cl <--> COC142- + H2O
2+
pink
blue
What happened when HCl was added?

See Explanation

Explanation:

In the equilibrium shown in the question,on the left hand side is a pink hexaaquacobalt II  complex which is pink in colour. On the right hand side, we have a tetrachlorocobalt II complex which is blue in colour.

The equilibrium can be shifted from left to right by adding HCl (a source of chloride ions).

Hence, when HCl is added to the system, the equilibrium position is shifted to the right thereby yielding the blue solution of the tetrachlorocobalt II complex.

i think a, hope it .

explanation:

i believe you are right for all except the 3rd ( look at sqdancefan his answer is much better)