Identify the ligand with the lowest field strength among the following.

Which among the following cations will form the lowest stability complex if the ligand remains the same?

Which compound is formed when an excess of $KCN$ is added to an aqueous solution of copper sulphate?

What is the color of the aqueous solution of $[Co(NH_3)_6]^{3+}$?

Which of the following complexes will be the most stable?

Assertion : $Cu^{2+}$ and $Cd^{2+}$ are separated from each other by first adding $KCN$ solution and then passing $H_2S$ gas.
Reason : $KCN$ reduces $Cu^{2+}$ to $Cu^{+}$ and forms a complex with it.