The complex ion `[Cu(NH_(3))_(4)]^(2+)` has

The complex ion [Cu(NH_3)_4]^(2+) is

Ammonia form the complex ion [Cu(NH_(3))_(4)]^(2+) with copper ions in the alkaline solution but not In acidic solution.What is the statement-2 for it?

In an excess of NH_(3(aq.)),Cu^(2+) ion form a deep blue complex ion [Cu(NH_(3))_(4)]^(2+) having formation constant K_(f)=5.6xx10^(11) . Calculate the concentration of Cu^(2+) in a solution prepared by adding 5.0xx10^(-3) mole of CuSO_(4) to 0.50 litre of 0.40M NH_(3) .

The complex [Cu(NH_(3))_(4)]^(2+) is :