[cu(nh3)4]2 forms a blue solution. when concentrated hcl is added to this solution, what color will the solution change to

Green.

Explanation:

Hello,

The tetra amine copper (II) cation is naturally blue due to the presence of copper and nitrogen into the solution. On the other hand, when chloride anions are added due to the hydrochloric acid addition, the formed species is whose color is green which is characteristic for copper and chlorine based salts (for example cupric chloride).

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b is the correct