Cobalt (III) chloride forms several octahedral complexes with ammonia. Which of the following will not give a test of chloride ions with silver nitrate at 25ºC? (AIPMT 2015)

3 3 CoCl .3NH will not give a test for chloride ions with silver nitrate at 25°C. The coordination number of Co is six. 3 ammonia ligands are present in the coordination sphere. Hence, 3 chloride ligands must be present in the coordination sphere. 3 3 CoCl .3NH can also be written as [CoCl3(NH3)3] Since, all the chloride ions are present in the coordination sphere, they are firmly attached to metal and do not ionize in solution. Hence, they cannot form precipitate of AgCl with AgNO3 solution.