The colour of $CoCl_3 \cdot 5NH_3 \cdot H_2O$ is

Which of the following statements is incorrect?

Which is the correct equation for the reaction of $AgCl$ with $NH_4OH$?

What is the coordination entity formed when excess of aqueous $KCN$ is added to an aqueous solution of copper sulphate? Why is it that no precipitate of copper sulphide is obtained when $H_{2}S_{(g)}$ is passed through this solution?

In an ammoniacal solution,copper ions form the complex ion $[Cu(NH_3)_4]^{2+}$,but this does not occur in an acidic solution. The reason for this is:

Which of the following statements is not correct?