Question

The radius of a calcium ion is 94 pm and of the oxide ion is 146 pm. Thepossible crystal structure of calcium oxide will be

• A. tetrahedral
• B. trigonal
• C. octahedral
• D. pyramidal

Answer 1

Answer: (C)

octahedral

Answer 2

As per formula, radius ratio $= \frac{\text{radius of cation}}{\text{radius of anion}}$ $= \frac{94}{146} = 0.643$ Since the value is between 0.414 - 0.732 hence the coordination no. will be 6 and geometry will be octahedral.