Question

Given: Radius of $A^{2+}=100\text{pm}$; Radius of $C^{+}=240\text{pm}$; Radius of $B^{2-}=300\text{pm}$; Radius of $D^{-}=480\text{pm}$. Which of the following statement(s) is/are correct?

• A. Coordination number of $A^{2+}$ in the compound AB is 4
• B. Coordination number of $A^{2+}$ in the compound AB is 6
• C. Coordination number of $C^{+}$ in the compound CD is 6
• D. Coordination number of $C^{+}$ in the compound CD is 8

Answer 1

Answer: (A), (C)

Coordination number of $C^{+}$ in the compound CD is 6

Radius ratio range: coordination number
0.155 - 0.225: 3
0.225 - 0.414: 4
0.414 - 0.732: 6
0.732 - 1.000: 8
Radius ratio of AB = $\frac{A^{2+}}{B^{2-}}=$$\frac{100}{300}$ = 0.33
Hence, coordination number = 4
Radius ratio of CD = $\frac{C^{+}}{D^{-}}=$$\frac{240}{480}$ = 0.5
Hence, coordination number = 6