Question

Barium ions, CNÆ and Co2+ form an ionic complex. If that complex is supposed to be 75% ionised in water with vant Hoff factor ‘i’ equal to four, then the coordination number of Co2+ in the complex can be :

• A. Six
• B. Five
• C. Four
• D. Six and Four both

Answer 1

Answer: (B)

Five

Answer 2

i = 1 + $\alpha$ (n – 1) or 4 = 1 + 0.75 (n – 1)

$\therefore$ n = 5 , so complex will be Ba3 [Co(CN)5]2.