Question

The radius of a calcium ion is 94 pm and of the oxide ion is 146 pm. The possible 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
$= \frac{radius\, of \,cation}{radius \,of \,anion}m$
$=\frac{94}{146}=0.643$
Since the value is between 0.414 - 0.732 hence the coordination no. will be 6 and geometry will be octahedral.
So, the correct option is (C): octahedral.